diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/README.md b/놀이터(예제 코드 작성)/solid-design-pattern-sample/README.md
new file mode 100644
index 0000000..faa5870
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/README.md	
@@ -0,0 +1,24 @@
+# SOLID & Design Pattern Sample
+
+## SOLID
+
+- SOLID 원칙들은 소프트웨어 작업에서 프로그래머가 소스 코드가 읽기 쉽고 확장하기 쉽게 될 때까지 소프트웨어 소스 코드를 리팩터링하여 코드 냄새를 제거하기 위해 적용할 수 있는 지침이다.
+- 각 항목별 before & after 를 비교하면서 어떤 차이가 있는지 생각해본다.
+- before & after 에 새로운, 또는 동일한 규칙(비즈니스 로직, 유효성 검사 등)을 적용해야 한다고 가정하고 변경을 시도해본다.
+
+### SRP(Single Responsibility Principle)
+
+- 단일 책임 원칙
+- 한 클래스는 하나의 책임만 가져야 한다. 즉, 한 클래스가 변경되는 이유는 한 가지여야 한다.
+
+#### 구현 요구사항
+
+- 예금주의 이름으로 계좌를 생성할 수 있다.
+- 계좌에 입금할 수 있다.
+- 계좌에서 출금할 수 있다.
+
+## 참고자료
+
+- [SOLID (객체 지향 설계)](https://ko.wikipedia.org/wiki/SOLID_(%EA%B0%9D%EC%B2%B4_%EC%A7%80%ED%96%A5_%EC%84%A4%EA%B3%84)) 
+
+
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/CreateAccountController.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/CreateAccountController.kt
new file mode 100644
index 0000000..f20011e
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/CreateAccountController.kt	
@@ -0,0 +1,18 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.after
+
+import com.banjjoknim.soliddesignpatternsample.solid.srp.common.Account
+import org.springframework.web.bind.annotation.PostMapping
+import org.springframework.web.bind.annotation.RequestBody
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RestController
+
+@RequestMapping("/accounts")
+@RestController
+class CreateAccountController(
+    private val createAccountService: CreateAccountService
+) {
+    @PostMapping("")
+    fun createAccount(@RequestBody request: CreateAccountRequest): Account {
+        return createAccountService.createAccount(request)
+    }
+}
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/CreateAccountRequest.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/CreateAccountRequest.kt
new file mode 100644
index 0000000..1ba5648
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/CreateAccountRequest.kt	
@@ -0,0 +1,5 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.after
+
+data class CreateAccountRequest(
+    val holderName: String
+)
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/CreateAccountService.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/CreateAccountService.kt
new file mode 100644
index 0000000..3347817
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/CreateAccountService.kt	
@@ -0,0 +1,14 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.after
+
+import com.banjjoknim.soliddesignpatternsample.solid.srp.common.Account
+import com.banjjoknim.soliddesignpatternsample.solid.srp.common.AccountRepository
+import org.springframework.stereotype.Service
+
+@Service
+class CreateAccountService(
+    private val accountRepository: AccountRepository
+) {
+    fun createAccount(request: CreateAccountRequest): Account {
+        return accountRepository.createAccount(request.holderName)
+    }
+}
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/DepositAccountController.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/DepositAccountController.kt
new file mode 100644
index 0000000..d9ec50a
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/DepositAccountController.kt	
@@ -0,0 +1,18 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.after
+
+import com.banjjoknim.soliddesignpatternsample.solid.srp.common.Account
+import org.springframework.web.bind.annotation.PatchMapping
+import org.springframework.web.bind.annotation.RequestBody
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RestController
+
+@RequestMapping("/accounts")
+@RestController
+class DepositAccountController(
+    private val depositAccountService: DepositAccountService
+) {
+    @PatchMapping("/deposit")
+    fun depositAccount(@RequestBody request: DepositAccountRequest): Account {
+        return depositAccountService.depositAccount(request)
+    }
+}
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/DepositAccountRequest.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/DepositAccountRequest.kt
new file mode 100644
index 0000000..cbe5060
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/DepositAccountRequest.kt	
@@ -0,0 +1,6 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.after
+
+data class DepositAccountRequest(
+    val accountId: Long,
+    val amount: Int
+)
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/DepositAccountService.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/DepositAccountService.kt
new file mode 100644
index 0000000..0516286
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/DepositAccountService.kt	
@@ -0,0 +1,16 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.after
+
+import com.banjjoknim.soliddesignpatternsample.solid.srp.common.Account
+import com.banjjoknim.soliddesignpatternsample.solid.srp.common.AccountRepository
+import org.springframework.stereotype.Service
+
+@Service
+class DepositAccountService(
+    private val accountRepository: AccountRepository
+) {
+    fun depositAccount(request: DepositAccountRequest): Account {
+        val account = accountRepository.findAccount(request.accountId)
+        account.deposit(request.amount)
+        return account
+    }
+}
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/WithdrawalAccountController.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/WithdrawalAccountController.kt
new file mode 100644
index 0000000..f65b2d5
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/WithdrawalAccountController.kt	
@@ -0,0 +1,18 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.after
+
+import com.banjjoknim.soliddesignpatternsample.solid.srp.common.Account
+import org.springframework.web.bind.annotation.PatchMapping
+import org.springframework.web.bind.annotation.RequestBody
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RestController
+
+@RequestMapping("/accounts")
+@RestController
+class WithdrawalAccountController(
+    private val withdrawalAccountService: WithdrawalAccountService
+) {
+    @PatchMapping("/withdrawal")
+    fun withdrawal(@RequestBody request: WithdrawalAccountRequest): Account {
+        return withdrawalAccountService.withdrawalAccount(request)
+    }
+}
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/WithdrawalAccountRequest.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/WithdrawalAccountRequest.kt
new file mode 100644
index 0000000..d4aa847
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/WithdrawalAccountRequest.kt	
@@ -0,0 +1,6 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.after
+
+data class WithdrawalAccountRequest(
+    val accountId: Long,
+    val amount: Int
+)
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/WithdrawalAccountService.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/WithdrawalAccountService.kt
new file mode 100644
index 0000000..09f106e
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/after/WithdrawalAccountService.kt	
@@ -0,0 +1,16 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.after
+
+import com.banjjoknim.soliddesignpatternsample.solid.srp.common.Account
+import com.banjjoknim.soliddesignpatternsample.solid.srp.common.AccountRepository
+import org.springframework.stereotype.Service
+
+@Service
+class WithdrawalAccountService(
+    private val accountRepository: AccountRepository
+) {
+    fun withdrawalAccount(request: WithdrawalAccountRequest): Account {
+        val account = accountRepository.findAccount(request.accountId)
+        account.withdrawal(request.amount)
+        return account
+    }
+}
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/before/AccountControllerBefore.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/before/AccountControllerBefore.kt
new file mode 100644
index 0000000..563d6db
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/before/AccountControllerBefore.kt	
@@ -0,0 +1,18 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.before
+
+import com.banjjoknim.soliddesignpatternsample.solid.srp.common.Account
+import org.springframework.web.bind.annotation.PatchMapping
+import org.springframework.web.bind.annotation.RequestBody
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RestController
+
+@RequestMapping("/accounts")
+@RestController
+class AccountControllerBefore(
+    private val accountServiceBefore: AccountServiceBefore
+) {
+    @PatchMapping("/manage-account-before")
+    fun manageAccount(@RequestBody request: ManageAccountRequest): Account {
+        return accountServiceBefore.manageAccount(request)
+    }
+}
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/before/AccountServiceBefore.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/before/AccountServiceBefore.kt
new file mode 100644
index 0000000..a314e83
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/before/AccountServiceBefore.kt	
@@ -0,0 +1,28 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.before
+
+import com.banjjoknim.soliddesignpatternsample.solid.srp.common.Account
+import com.banjjoknim.soliddesignpatternsample.solid.srp.common.AccountRepository
+import org.springframework.stereotype.Service
+
+@Service
+class AccountServiceBefore(
+    private val accountRepository: AccountRepository
+) {
+    fun manageAccount(request: ManageAccountRequest): Account {
+        return when (request.type) {
+            ManageAccountType.CREATE -> {
+                accountRepository.createAccount(request.holderName)
+            }
+            ManageAccountType.DEPOSIT -> {
+                val account = accountRepository.findAccount(request.accountId)
+                account.deposit(request.amount)
+                account
+            }
+            ManageAccountType.WITHDRAWAL -> {
+                val account = accountRepository.findAccount(request.accountId)
+                account.withdrawal(request.amount)
+                account
+            }
+        }
+    }
+}
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/before/ManageAccountRequest.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/before/ManageAccountRequest.kt
new file mode 100644
index 0000000..1df3022
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/before/ManageAccountRequest.kt	
@@ -0,0 +1,8 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.before
+
+data class ManageAccountRequest(
+    val accountId: Long,
+    val holderName: String,
+    val amount: Int,
+    val type: ManageAccountType
+)
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/before/ManageAccountType.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/before/ManageAccountType.kt
new file mode 100644
index 0000000..f96e605
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/before/ManageAccountType.kt	
@@ -0,0 +1,7 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.before
+
+enum class ManageAccountType {
+    CREATE, // 생성
+    DEPOSIT, // 입금
+    WITHDRAWAL // 출금
+}
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/common/Account.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/common/Account.kt
new file mode 100644
index 0000000..d650ecd
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/common/Account.kt	
@@ -0,0 +1,20 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.common
+
+import javax.persistence.Entity
+import javax.persistence.Id
+
+@Entity
+class Account(
+    val holderName: String = "",
+    var balance: Int = 0,
+    @Id
+    val id: Long = 0,
+) {
+    fun deposit(amount: Int) {
+        this.balance = this.balance + amount
+    }
+
+    fun withdrawal(amount: Int) {
+        this.balance = this.balance - amount
+    }
+}
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/common/AccountRepository.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/common/AccountRepository.kt
new file mode 100644
index 0000000..aa0e27e
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/common/AccountRepository.kt	
@@ -0,0 +1,7 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.common
+
+interface AccountRepository {
+    fun createAccount(holderName: String): Account
+
+    fun findAccount(accountId: Long): Account
+}
diff --git a/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/common/AccountRepositoryStub.kt b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/common/AccountRepositoryStub.kt
new file mode 100644
index 0000000..54dfdb2
--- /dev/null
+++ b/놀이터(예제 코드 작성)/solid-design-pattern-sample/src/main/kotlin/com/banjjoknim/soliddesignpatternsample/solid/srp/common/AccountRepositoryStub.kt	
@@ -0,0 +1,14 @@
+package com.banjjoknim.soliddesignpatternsample.solid.srp.common
+
+import org.springframework.stereotype.Repository
+
+@Repository
+class AccountRepositoryStub : AccountRepository {
+    override fun createAccount(holderName: String): Account {
+        return Account(holderName = "banjjoknim", balance = 0)
+    }
+
+    override fun findAccount(accountId: Long): Account {
+        return Account(id = 1L, balance = 10000)
+    }
+}