diff --git a/public/robots.txt b/public/robots.txt
new file mode 100644
index 00000000..1cb1c273
--- /dev/null
+++ b/public/robots.txt
@@ -0,0 +1,8 @@
+User-agent: *
+Allow: /
+
+# Sitemap
+Sitemap: https://www.devpals.site/sitemap.xml
+
+# Crawl-delay (선택사항)
+Crawl-delay: 1 
\ No newline at end of file
diff --git a/public/sitemap.xml b/public/sitemap.xml
new file mode 100644
index 00000000..3cb11ee5
--- /dev/null
+++ b/public/sitemap.xml
@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
+  <url>
+    <loc>https://www.devpals.site/</loc>
+    <lastmod>2024-01-01</lastmod>
+    <changefreq>daily</changefreq>
+    <priority>1.0</priority>
+  </url>
+  <url>
+    <loc>https://www.devpals.site/main</loc>
+    <lastmod>2024-01-01</lastmod>
+    <changefreq>daily</changefreq>
+    <priority>0.9</priority>
+  </url>
+  <url>
+    <loc>https://www.devpals.site</loc>
+    <lastmod>2024-01-01</lastmod>
+    <changefreq>weekly</changefreq>
+    <priority>0.7</priority>
+  </url>
+</urlset> 
\ No newline at end of file
diff --git a/src/components/common/avatar/Avatar.tsx b/src/components/common/avatar/Avatar.tsx
index 61accdcc..6b7e8e45 100644
--- a/src/components/common/avatar/Avatar.tsx
+++ b/src/components/common/avatar/Avatar.tsx
@@ -5,15 +5,16 @@ import defaultImg from '../../../assets/defaultImg.png';
 export interface AvatarProps {
   size: string;
   image: string | ReactNode;
+  alt?: string;
 }
 
-function Avatar({ size, image }: AvatarProps) {
+function Avatar({ size, image, alt = '사용자 프로필 이미지' }: AvatarProps) {
   const releasedImg =
     typeof image === 'string' && image.trim() ? image : defaultImg;
   return (
     <S.AvatarContainer size={size}>
       {typeof image === 'string' || !image ? (
-        <S.AvatarImg src={releasedImg} alt='Avatar' />
+        <S.AvatarImg src={releasedImg} alt={alt} />
       ) : (
         image
       )}
diff --git a/src/hooks/useIsMobile.ts b/src/hooks/useIsMobile.ts
new file mode 100644
index 00000000..38f40e56
--- /dev/null
+++ b/src/hooks/useIsMobile.ts
@@ -0,0 +1,26 @@
+import { useState, useEffect } from 'react';
+
+const useIsMobile = () => {
+  const [isMobile, setIsMobile] = useState(false);
+
+  useEffect(() => {
+    const checkIsMobile = () => {
+      setIsMobile(window.innerWidth <= 768);
+    };
+
+    // 초기 체크
+    checkIsMobile();
+
+    // 리사이즈 이벤트 리스너 추가
+    window.addEventListener('resize', checkIsMobile);
+
+    // 클린업 함수
+    return () => {
+      window.removeEventListener('resize', checkIsMobile);
+    };
+  }, []);
+
+  return isMobile;
+};
+
+export default useIsMobile;
diff --git a/src/hooks/user/CommentHooks/usePostComment.ts b/src/hooks/user/CommentHooks/usePostComment.ts
index 5113c039..fffbf6a0 100644
--- a/src/hooks/user/CommentHooks/usePostComment.ts
+++ b/src/hooks/user/CommentHooks/usePostComment.ts
@@ -10,7 +10,7 @@ const usePostComment = (id: number) => {
     onSuccess: () => {
       queryClient.invalidateQueries({
         queryKey: [ProjectCommentList.projectComment, id],
-        exact: true,
+        exact: false,
       });
     },
     onError: (error) => {
diff --git a/src/pages/user/apply/Apply.tsx b/src/pages/user/apply/Apply.tsx
index 043074c4..98db5326 100644
--- a/src/pages/user/apply/Apply.tsx
+++ b/src/pages/user/apply/Apply.tsx
@@ -15,6 +15,8 @@ import LoadingSpinner from '../../../components/common/loadingSpinner/LoadingSpi
 import PhoneComponent from '../../../components/user/applyComponents/phoneComponent/PhoneComponent';
 import CareersComponent from '../../../components/user/applyComponents/careersComponent/CareersComponent';
 import Input from '../../../components/user/projectFormComponents/inputComponent/InputComponent';
+import ApplyStep from './ApplyStep';
+import useIsMobile from '../../../hooks/useIsMobile';
 
 const Apply = () => {
   const { projectId } = useParams();
@@ -23,6 +25,7 @@ const Apply = () => {
   const { data: projectData, isLoading, isFetching } = useGetProjectData(id);
   const { applyProject } = useApplyProject({ id, handleModalOpen });
   const userEmail = useAuthStore((state) => state.userData?.email);
+  const isMobile = useIsMobile();
 
   const {
     handleSubmit: onSubmitHandler,
@@ -65,6 +68,12 @@ const Apply = () => {
   if (isLoading) return <LoadingSpinner />;
   if (isFetching) return <LoadingSpinner />;
 
+  // 모바일 환경이면 ApplyStep 컴포넌트 렌더링
+  if (isMobile) {
+    return <ApplyStep />;
+  }
+
+  // 데스크톱 환경이면 기존 Apply 컴포넌트 렌더링
   return (
     <S.Container>
       <S.Title>프로젝트 지원</S.Title>
diff --git a/src/pages/user/projectDetail/ProjectDetail.tsx b/src/pages/user/projectDetail/ProjectDetail.tsx
index d395f152..3e13bc4b 100644
--- a/src/pages/user/projectDetail/ProjectDetail.tsx
+++ b/src/pages/user/projectDetail/ProjectDetail.tsx
@@ -31,6 +31,29 @@ const ProjectDetail = () => {
     }
   }, [data, handleModalOpen, isLoading, isFetching]);
 
+  // 간단한 메타 정보 설정
+  useEffect(() => {
+    if (data) {
+      document.title = `${data.title} - 프로젝트 상세`;
+
+      // 메타 설명 추가
+      const metaDescription = document.querySelector(
+        'meta[name="description"]'
+      );
+      if (metaDescription) {
+        metaDescription.setAttribute(
+          'content',
+          `${data.title} 프로젝트에 대한 상세 정보입니다.`
+        );
+      } else {
+        const newMetaDescription = document.createElement('meta');
+        newMetaDescription.name = 'description';
+        newMetaDescription.content = `${data.title} 프로젝트에 대한 상세 정보입니다.`;
+        document.head.appendChild(newMetaDescription);
+      }
+    }
+  }, [data]);
+
   if (isLoading || isFetching) return <LoadingSpinner />;
 
   if (!data) {
@@ -63,7 +86,11 @@ const ProjectDetail = () => {
             <S.Title>{data.title}</S.Title>
             <S.ProfileContainer>
               <S.ProfileImageContainer onClick={handleMovetoUserPage}>
-                <Avatar size='2.5rem' image={data.user.img} />
+                <Avatar
+                  size='2.5rem'
+                  image={data.user.img}
+                  alt={`${data.user.nickname}의 프로필 이미지`}
+                />
               </S.ProfileImageContainer>
               <S.UserInfo>
                 <S.UserName onClick={handleMovetoUserPage}>
@@ -71,19 +98,21 @@ const ProjectDetail = () => {
                 </S.UserName>
                 <S.PostDate>{formatDate(data.recruitmentEndDate)}</S.PostDate>
                 <S.ViewCount>
-                  <EyeIcon />
+                  <EyeIcon aria-label='조회수' />
                   {data.views}
                 </S.ViewCount>
               </S.UserInfo>
             </S.ProfileContainer>
           </S.Header>
+
           <S.Content>
             <ProjectInformation data={data} />
-            <br></br>
+            <br />
             <S.ProjectDescription>
               <MarkdownEditorView description={data.description} />
             </S.ProjectDescription>
           </S.Content>
+
           <S.ApplyButtonContainer>
             {userData &&
             userData.id !== data.user.id &&
@@ -99,7 +128,9 @@ const ProjectDetail = () => {
               </Button>
             ) : null}
           </S.ApplyButtonContainer>
-          <hr></hr>
+
+          <hr />
+
           <CommentLayout
             projectId={data.id}
             createrId={data.user.id}
@@ -107,6 +138,7 @@ const ProjectDetail = () => {
           />
         </S.Wrapper>
       </S.Container>
+
       <Modal
         isOpen={isOpen}
         onClose={handleModalClose}
diff --git a/src/routes/AppRoutes.tsx b/src/routes/AppRoutes.tsx
index df3f7d86..0f76821d 100644
--- a/src/routes/AppRoutes.tsx
+++ b/src/routes/AppRoutes.tsx
@@ -27,7 +27,7 @@ const Inquiry = lazy(
 );
 const MyPage = lazy(() => import('../pages/user/mypage/MyPage'));
 const UserPage = lazy(() => import('../pages/user/userpage/UserPage'));
-const Apply = lazy(() => import('../pages/user/apply/ApplyStep'));
+const Apply = lazy(() => import('../pages/user/apply/Apply'));
 const CreateProject = lazy(
   () => import('../pages/user/createProject/CreateProject')
 );