diff --git a/blockchain/nft-ex/index.html b/blockchain/nft-ex/index.html
index 6b622874..def19581 100644
--- a/blockchain/nft-ex/index.html
+++ b/blockchain/nft-ex/index.html
@@ -29,6 +29,20 @@
     <script>
 
         $(window).load(async function () {
+            var contractAddress;
+            //블록체인 네트워크 선택하기
+            var blockChainNetwork = localStorage.getItem("blockChainNetwork")
+            $("#selectNetwork").val(blockChainNetwork).prop("selected", true);
+
+
+            if (blockChainNetwork == "MATIC_MUMBAI") {
+                contractAddress = contractAddress_MATIC_MUMBAI;
+            }
+
+            else if (blockChainNetwork == "ETH_RINKEBY") {
+                contractAddress = contractAddress_ETH_RINKEBY;
+            }
+
         
             if (typeof web3 !== "undefined") {
                 console.log("web3가 활성화되었습니다");
diff --git a/blockchain/nft-ex/js/abi.js b/blockchain/nft-ex/js/abi.js
index 050f8ff2..574e56df 100644
--- a/blockchain/nft-ex/js/abi.js
+++ b/blockchain/nft-ex/js/abi.js
@@ -610,4 +610,5 @@ const abiobj = [
 	}
 ];
 
-let contractAddress = "0x0155B13063957e66dE19ea2B00f8Fc6E299b8A9C";
\ No newline at end of file
+let contractAddress_MATIC_MUMBAI = "0x0155B13063957e66dE19ea2B00f8Fc6E299b8A9C";
+let contractAddress_ETH_RINKEBY = "0x0155B13063957e66dE19ea2B00f8Fc6E299b8A9C";
\ No newline at end of file
diff --git a/blockchain/nft-ex/js/jscript.js b/blockchain/nft-ex/js/jscript.js
index 3d3b76d2..c79735f1 100644
--- a/blockchain/nft-ex/js/jscript.js
+++ b/blockchain/nft-ex/js/jscript.js
@@ -7,12 +7,22 @@ $(document).ready(function () {
     $("#page_mynft").on("click", function () {
       window.location.href = "./mynft.html";
     });
+
+    $("#selectNetwork").change(function () {
+      var blockChainNetwork = $("#selectNetwork option:selected").val();
+      if (!blockChainNetwork) {
+        alert("네트워크를 선택해주세요!");
+      } else {
+        localStorage["blockChainNetwork"] = blockChainNetwork;
+      }
+    });
 });
 
 function onlyNumber(){
   if((event.keyCode > 48 && event.keyCode < 57 ) 
      || event.keyCode == 8 
-     || event.keyCode == 37 || event.keyCode == 39 
+     || event.keyCode == 37 
+     || event.keyCode == 39 
      || event.keyCode == 46 
      || event.keyCode == 39){
   }else{
diff --git a/blockchain/nft-ex/mynft.html b/blockchain/nft-ex/mynft.html
index 9e9b7dbc..2f8ba685 100644
--- a/blockchain/nft-ex/mynft.html
+++ b/blockchain/nft-ex/mynft.html
@@ -26,6 +26,20 @@
 
         $(window).load(async function () {
 
+            var contractAddress;
+            //블록체인 네트워크 선택하기
+            var blockChainNetwork = localStorage.getItem("blockChainNetwork")
+            $("#selectNetwork").val(blockChainNetwork).prop("selected", true);
+
+
+            if (blockChainNetwork == "MATIC_MUMBAI") {
+                contractAddress = contractAddress_MATIC_MUMBAI;
+            }
+
+            else if (blockChainNetwork == "ETH_RINKEBY") {
+                contractAddress = contractAddress_ETH_RINKEBY;
+            }
+
             if (typeof web3 !== "undefined") {
                 console.log("web3가 활성화되었습니다");
 
diff --git a/blockchain/nft-ex/mynft_detail.html b/blockchain/nft-ex/mynft_detail.html
index bf307120..73a1a386 100644
--- a/blockchain/nft-ex/mynft_detail.html
+++ b/blockchain/nft-ex/mynft_detail.html
@@ -26,6 +26,20 @@
 
         $(window).load(async function () {
 
+            var contractAddress;
+            //블록체인 네트워크 선택하기
+            var blockChainNetwork = localStorage.getItem("blockChainNetwork")
+            $("#selectNetwork").val(blockChainNetwork).prop("selected", true);
+
+
+            if (blockChainNetwork == "MATIC_MUMBAI") {
+                contractAddress = contractAddress_MATIC_MUMBAI;
+            }
+
+            else if (blockChainNetwork == "ETH_RINKEBY") {
+                contractAddress = contractAddress_ETH_RINKEBY;
+            }
+
             if (typeof web3 !== "undefined") {
                 console.log("web3가 활성화되었습니다");
 
diff --git a/blockchain/nft-ex/sale.html b/blockchain/nft-ex/sale.html
index 389ba07a..5c4504ae 100644
--- a/blockchain/nft-ex/sale.html
+++ b/blockchain/nft-ex/sale.html
@@ -29,6 +29,20 @@
     <script>
 
         $(window).load(async function () {
+
+            var contractAddress;
+            //블록체인 네트워크 선택하기
+            var blockChainNetwork = localStorage.getItem("blockChainNetwork")
+            $("#selectNetwork").val(blockChainNetwork).prop("selected", true);
+
+
+            if (blockChainNetwork == "MATIC_MUMBAI") {
+                contractAddress = contractAddress_MATIC_MUMBAI;
+            }
+
+            else if (blockChainNetwork == "ETH_RINKEBY") {
+                contractAddress = contractAddress_ETH_RINKEBY;
+            }
         
             if (typeof web3 !== "undefined") {
                 console.log("web3가 활성화되었습니다");