diff --git a/css/login.css b/css/login.css
index 4700b03dc..8495f83ce 100644
--- a/css/login.css
+++ b/css/login.css
@@ -40,13 +40,26 @@ input {
 }
 
 input:focus {
-  outline: 2px solid var(--brand-blue);
+  outline: 1px solid var(--brand-blue);
+}
+
+.error-input,
+.error-input:focus {
+  outline: 1px solid var(--error-red);
 }
 
 .password-input {
   position: relative;
 }
 
+.error-message {
+  margin-top: 8px;
+  margin-left: 16px;
+  font-size: 15px;
+  font-weight: 600;
+  color: var(--error-red);
+}
+
 .visibility-button {
   width: 24px;
   height: 24px;
diff --git a/js/button.js b/js/button.js
new file mode 100644
index 000000000..4e1d213ec
--- /dev/null
+++ b/js/button.js
@@ -0,0 +1,25 @@
+// validitiy checker (boolean)
+import { emailIsValid, nicknameIsValid, pwIsValid, pwRetypeIsValid } from './input.js';
+
+const loginButton = document.querySelector('#login-button');
+const signupButton = document.querySelector('#signup-button');
+
+// every input is valid -> button disable=false
+export function buttonDisableChecker(event) {
+
+  if(loginButton !== null) {
+    if(emailIsValid && pwIsValid) {
+      loginButton.disabled = false;
+    } else {
+      loginButton.disabled = true;
+    }
+  }
+
+  if(signupButton !== null) {
+    if(emailIsValid && pwIsValid && nicknameIsValid && pwRetypeIsValid) {
+      signupButton.disabled = false;
+    } else {
+      signupButton.disabled = true;
+    }
+  }
+}
\ No newline at end of file
diff --git a/js/input.js b/js/input.js
new file mode 100644
index 000000000..60fdf4b7b
--- /dev/null
+++ b/js/input.js
@@ -0,0 +1,86 @@
+// password valid condition
+const PW_MIN_LENGTH = 8;
+
+// for button disable toggle
+export let emailIsValid = false;
+export let nicknameIsValid = false;
+export let pwIsValid = false;
+export let pwRetypeIsValid = false;
+
+// email validitiychecker
+export function emailInputCheck(event) {
+  const target = event.target;
+  const errorMessage = document.querySelector('#email-error-message');
+
+  if (target.value === "") {
+    target.classList.add('error-input');
+    errorMessage.textContent = '이메일을 입력해주세요.';
+    emailIsValid = false;
+  }
+  // checkValidity() : true ("" or type match), false (different type)
+  if (!target.checkValidity()) {
+    target.classList.add('error-input');
+    errorMessage.textContent = '잘못된 이메일 형식입니다.';
+    emailIsValid = false;
+  }
+  if (target.checkValidity() && target.value !== "") {
+    target.classList.remove('error-input');
+    errorMessage.textContent = '';
+    emailIsValid = true;
+  }
+}
+
+// nickname validitiychecker
+export function nicknameInputCheck(event) {
+  const target = event.target;
+  const errorMessage = document.querySelector('#nickname-error-message');
+
+  if (target.value === "") {
+    target.classList.add('error-input');
+    errorMessage.textContent = '닉네임을 입력해주세요.';
+    nicknameIsValid = false;
+  } else {
+    target.classList.remove('error-input');
+    errorMessage.textContent = '';
+    nicknameIsValid = true;
+  }
+}
+
+// password validitiychecker
+export function pwInputCheck(event) {
+  const target = event.target;
+  const errorMessage = document.querySelector('#password-error-message');
+
+  if (target.value.length === 0) {
+    target.classList.add('error-input');
+    errorMessage.textContent = '비밀번호를 입력해주세요.';
+    pwIsValid = false;
+  }
+  if (target.value.length < PW_MIN_LENGTH && target.value.length > 0) {
+    target.classList.add('error-input');
+    errorMessage.textContent = '비밀번호를 8자 이상 입력해주세요.';
+    pwIsValid = false;
+  }
+  if (target.value.length >= PW_MIN_LENGTH) {
+    target.classList.remove('error-input');
+    errorMessage.textContent = '';
+    pwIsValid = true;
+  }
+}
+
+// retype password validitiychecker
+export function pwRetypeInputCheck(event) {
+  const target = event.target;
+  const pwInput = document.querySelector('#password-input');
+  const errorMessage = document.querySelector('#password-retype-error-message');
+
+  if (target.value !== pwInput.value) {
+    target.classList.add('error-input');
+    errorMessage.textContent = '비밀번호가 일치하지 않습니다.';
+    pwRetypeIsValid = false;
+  } else {
+    target.classList.remove('error-input');
+    errorMessage.textContent = '';
+    pwRetypeIsValid = true;
+  }
+}
\ No newline at end of file
diff --git a/js/main.js b/js/main.js
new file mode 100644
index 000000000..4112869af
--- /dev/null
+++ b/js/main.js
@@ -0,0 +1,32 @@
+import { emailInputCheck,nicknameInputCheck, pwInputCheck, pwRetypeInputCheck } from './input.js';
+import { buttonDisableChecker } from './button.js';
+import { pwVisibleToggle } from './pw_visibility.js';
+
+const emailInput = document.querySelector('#email-input');
+const pwInput = document.querySelector('#password-input');
+const pwRetypeInput = document.querySelector('#password-retype-input');
+const nicknameInput = document.querySelector('#nickname-input');
+
+const pwVisibleBtn = document.querySelector('#password-visibility-button');
+const pwRetypeVisibleBtn = document.querySelector('#password-retype-visibility-button');
+
+// login page event
+emailInput.addEventListener('focusout', emailInputCheck);
+pwInput.addEventListener('focusout', pwInputCheck);
+
+emailInput.addEventListener('focusout', buttonDisableChecker);
+pwInput.addEventListener('focusout', buttonDisableChecker);
+
+pwVisibleBtn.addEventListener('click', pwVisibleToggle);
+
+
+// additional event for signup page
+if (pwRetypeInput && nicknameInput) {
+  nicknameInput.addEventListener('focusout', nicknameInputCheck);
+  pwRetypeInput.addEventListener('focusout', pwRetypeInputCheck);
+
+  nicknameInput.addEventListener('focusout', buttonDisableChecker);
+  pwRetypeInput.addEventListener('focusout', buttonDisableChecker);
+
+  pwRetypeVisibleBtn.addEventListener('click', pwVisibleToggle);
+}
\ No newline at end of file
diff --git a/js/pw_visibility.js b/js/pw_visibility.js
new file mode 100644
index 000000000..aecd694a6
--- /dev/null
+++ b/js/pw_visibility.js
@@ -0,0 +1,17 @@
+let visibleMode = false;
+
+export function pwVisibleToggle(event) {
+  const img = event.target;
+  const input = img.parentElement.parentElement.firstElementChild;
+
+  if (visibleMode) {
+    img.src = "/images/btn_visibility_off.png";
+    input.type = "password";
+    visibleMode = false;
+  } else {
+    img.src = "/images/btn_visibility_on.png";
+    input.type = "text";
+    visibleMode = true;
+  }
+}
+
diff --git a/pages/login/index.html b/pages/login/index.html
index 71f3a2084..fabee9f84 100644
--- a/pages/login/index.html
+++ b/pages/login/index.html
@@ -14,6 +14,7 @@
     <link rel="stylesheet" href="/css/base/global.css" />
     <link rel="stylesheet" href="/css/login.css" />
   </head>
+
   <body>
     <header>
       <div class="logo-block">
@@ -26,30 +27,33 @@
       <div class="content">
         <div>
           <h3>이메일</h3>
-          <input type="email"
+          <input type="email" id="email-input"
            placeholder="이메일을 입력해주세요"
            onfocus="this.placeholder=''"
            onblur="this.placeholder='이메일을 입력해주세요'"
           />
+          <p id="email-error-message" class="error-message"></p>
         </div>
         <div>
           <h3>비밀번호</h3>
           <div class="password-input">
-            <input type="password"
+            <input type="password" id="password-input"
              placeholder="비밀번호를 입력해주세요"
              onfocus="this.placeholder=''"
              onblur="this.placeholder='비밀번호를 입력해주세요'"
-            />
+            /> 
             <a>
               <img
-                  class="visibility-button"
-                  src="/images/btn_visibility_off.png"
-                  alt="비밀번호 표시 옵션"
+                id="password-visibility-button"
+                class="visibility-button"
+                src="/images/btn_visibility_off.png"
+                alt="비밀번호 표시 옵션"
               />
             </a>
+            <p id="password-error-message" class="error-message"></p>
           </div>
         </div>
-        <button>로그인</button>
+        <button id="login-button" onclick="location.href='/pages/items'" disabled="true">로그인</button>
         <div class="simple-login">
           <p>
             간편 로그인하기
@@ -70,4 +74,8 @@ <h3>비밀번호</h3>
       </div>
     </main>
   </body>
+
+  <script type="module" src="/js/main.js"></script>
+  <script type="module" src="/js/input.js"></script>
+  <script type="module" src="/js/pw_visibility.js"></script>
 </html>
\ No newline at end of file
diff --git a/pages/login/signup.html b/pages/login/signup.html
index 2e9b973e2..55525026d 100644
--- a/pages/login/signup.html
+++ b/pages/login/signup.html
@@ -14,6 +14,7 @@
     <link rel="stylesheet" href="/css/base/global.css" />
     <link rel="stylesheet" href="/css/login.css" />
   </head>
+
   <body>
     <header>
       <div class="logo-block">
@@ -26,55 +27,61 @@
       <div class="content">
         <div>
           <h3>이메일</h3>
-          <input type="email"
+          <input type="email" id="email-input"
            placeholder="이메일을 입력해주세요"
            onfocus="this.placeholder=''"
            onblur="this.placeholder='이메일을 입력해주세요'"
           />
+          <p id="email-error-message" class="error-message"></p>
         </div>
         <div>
           <h3>닉네임</h3>
-          <input type="text"
+          <input type="text" id="nickname-input"
            placeholder="닉네임을 입력해주세요"
            onfocus="this.placeholder=''"
            onblur="this.placeholder='닉네임을 입력해주세요'"
           />
+          <p id="nickname-error-message" class="error-message"></p>
         </div>
         <div>
           <h3>비밀번호</h3>
           <div class="password-input">
-            <input type="password"
+            <input type="password" id="password-input"
              placeholder="비밀번호를 입력해주세요"
              onfocus="this.placeholder=''"
              onblur="this.placeholder='비밀번호를 입력해주세요'"
             />
             <a>
               <img
-                  class="visibility-button"
-                  src="/images/btn_visibility_off.png"
-                  alt="비밀번호 표시 옵션"
+                id="password-visibility-button"
+                class="visibility-button"
+                src="/images/btn_visibility_off.png"
+                alt="비밀번호 표시 옵션"
               />
             </a>
+            <p id="password-error-message" class="error-message"></p>
           </div>
         </div>
         <div>
           <h3>비밀번호 확인</h3>
           <div class="password-input">
-            <input type="password"
+            <input type="password" id="password-retype-input"
              placeholder="비밀번호를 다시 한 번 입력해주세요"
              onfocus="this.placeholder=''"
              onblur="this.placeholder='비밀번호를 다시 한 번 입력해주세요'"
             />
             <a>
               <img
-                  class="visibility-button"
-                  src="/images/btn_visibility_off.png"
-                  alt="비밀번호 표시 옵션"
+                id="password-retype-visibility-button"
+                class="visibility-button"
+                src="/images/btn_visibility_off.png"
+                alt="비밀번호 표시 옵션"
               />
             </a>
+            <p id="password-retype-error-message" class="error-message"></p>
           </div>
         </div>
-        <button>회원가입</button>
+        <button id="signup-button" onclick="location.href='./'" disabled>회원가입</button>
         <div class="simple-login">
           <p>
             간편 로그인하기
@@ -95,4 +102,8 @@ <h3>비밀번호 확인</h3>
       </div>
     </main>
   </body>
+
+  <script type="module" src="/js/main.js"></script>
+  <script type="module" src="/js/input.js"></script>
+  <script type="module" src="/js/pw_visibility.js"></script>
 </html>
\ No newline at end of file