diff --git a/src/main/kotlin/dev/usbharu/hideout/controller/NoteApController.kt b/src/main/kotlin/dev/usbharu/hideout/controller/NoteApController.kt
new file mode 100644
index 00000000..f7fe6197
--- /dev/null
+++ b/src/main/kotlin/dev/usbharu/hideout/controller/NoteApController.kt
@@ -0,0 +1,16 @@
+package dev.usbharu.hideout.controller
+
+import dev.usbharu.hideout.domain.model.ap.Note
+import org.springframework.http.ResponseEntity
+import org.springframework.security.core.annotation.CurrentSecurityContext
+import org.springframework.security.core.context.SecurityContext
+import org.springframework.web.bind.annotation.GetMapping
+import org.springframework.web.bind.annotation.PathVariable
+
+interface NoteApController {
+    @GetMapping("/users/*/posts/{postId}")
+    suspend fun postsAp(
+        @PathVariable("postId") postId: Long,
+        @CurrentSecurityContext context: SecurityContext
+    ): ResponseEntity<Note>
+}
diff --git a/src/main/kotlin/dev/usbharu/hideout/controller/NoteApControllerImpl.kt b/src/main/kotlin/dev/usbharu/hideout/controller/NoteApControllerImpl.kt
new file mode 100644
index 00000000..76bd6d63
--- /dev/null
+++ b/src/main/kotlin/dev/usbharu/hideout/controller/NoteApControllerImpl.kt
@@ -0,0 +1,32 @@
+package dev.usbharu.hideout.controller
+
+import dev.usbharu.hideout.domain.model.ap.Note
+import dev.usbharu.hideout.service.api.NoteApApiService
+import dev.usbharu.hideout.service.signature.HttpSignatureUser
+import org.springframework.http.ResponseEntity
+import org.springframework.security.core.annotation.CurrentSecurityContext
+import org.springframework.security.core.context.SecurityContext
+import org.springframework.security.web.authentication.preauth.PreAuthenticatedAuthenticationToken
+import org.springframework.web.bind.annotation.PathVariable
+import org.springframework.web.bind.annotation.RestController
+
+@RestController
+class NoteApControllerImpl(private val noteApApiService: NoteApApiService) : NoteApController {
+    override suspend fun postsAp(
+        @PathVariable(value = "postId") postId: Long, @CurrentSecurityContext context: SecurityContext
+    ): ResponseEntity<Note> {
+
+        val userId =
+            if (context.authentication is PreAuthenticatedAuthenticationToken && context.authentication.details is HttpSignatureUser) {
+                (context.authentication.details as HttpSignatureUser).id
+            } else {
+                null
+            }
+
+        val note = noteApApiService.getNote(postId, userId)
+        if (note != null) {
+            return ResponseEntity.ok(note)
+        }
+        return ResponseEntity.notFound().build()
+    }
+}
diff --git a/src/main/kotlin/dev/usbharu/hideout/query/FollowerQueryService.kt b/src/main/kotlin/dev/usbharu/hideout/query/FollowerQueryService.kt
index 4cc73ef1..4922b268 100644
--- a/src/main/kotlin/dev/usbharu/hideout/query/FollowerQueryService.kt
+++ b/src/main/kotlin/dev/usbharu/hideout/query/FollowerQueryService.kt
@@ -1,9 +1,7 @@
 package dev.usbharu.hideout.query
 
 import dev.usbharu.hideout.domain.model.hideout.entity.User
-import org.springframework.stereotype.Repository
 
-@Repository
 interface FollowerQueryService {
     suspend fun findFollowersById(id: Long): List<User>
     suspend fun findFollowersByNameAndDomain(name: String, domain: String): List<User>
diff --git a/src/main/kotlin/dev/usbharu/hideout/query/activitypub/NoteQueryService.kt b/src/main/kotlin/dev/usbharu/hideout/query/activitypub/NoteQueryService.kt
new file mode 100644
index 00000000..d0ee3adb
--- /dev/null
+++ b/src/main/kotlin/dev/usbharu/hideout/query/activitypub/NoteQueryService.kt
@@ -0,0 +1,8 @@
+package dev.usbharu.hideout.query.activitypub
+
+import dev.usbharu.hideout.domain.model.ap.Note
+import dev.usbharu.hideout.domain.model.hideout.entity.Post
+
+interface NoteQueryService {
+    suspend fun findById(id: Long): Pair<Note, Post>
+}
diff --git a/src/main/kotlin/dev/usbharu/hideout/query/activitypub/NoteQueryServiceImpl.kt b/src/main/kotlin/dev/usbharu/hideout/query/activitypub/NoteQueryServiceImpl.kt
new file mode 100644
index 00000000..1ee6d038
--- /dev/null
+++ b/src/main/kotlin/dev/usbharu/hideout/query/activitypub/NoteQueryServiceImpl.kt
@@ -0,0 +1,39 @@
+package dev.usbharu.hideout.query.activitypub
+
+import dev.usbharu.hideout.domain.model.ap.Note
+import dev.usbharu.hideout.domain.model.hideout.entity.Post
+import dev.usbharu.hideout.exception.FailedToGetResourcesException
+import dev.usbharu.hideout.repository.Posts
+import dev.usbharu.hideout.repository.Users
+import dev.usbharu.hideout.repository.toPost
+import dev.usbharu.hideout.util.singleOr
+import org.jetbrains.exposed.sql.ResultRow
+import org.jetbrains.exposed.sql.select
+import org.springframework.stereotype.Repository
+import java.time.Instant
+
+@Repository
+class NoteQueryServiceImpl : NoteQueryService {
+    override suspend fun findById(id: Long): Pair<Note, Post> {
+        return Posts
+            .leftJoin(Users)
+            .select { Posts.id eq id }
+            .singleOr { FailedToGetResourcesException("id $id is duplicate or does not exist.") }
+            .let { it.toNote() to it.toPost() }
+
+    }
+
+    private fun ResultRow.toNote(): Note {
+        return Note(
+            name = "Post",
+            id = this[Posts.apId],
+            attributedTo = this[Users.url],
+            content = this[Posts.text],
+            published = Instant.ofEpochMilli(this[Posts.createdAt]).toString(),
+            to = listOf(),
+            cc = listOf(),
+            inReplyTo = null,
+            sensitive = false
+        )
+    }
+}
diff --git a/src/main/kotlin/dev/usbharu/hideout/service/api/NoteApApiService.kt b/src/main/kotlin/dev/usbharu/hideout/service/api/NoteApApiService.kt
new file mode 100644
index 00000000..38006f4b
--- /dev/null
+++ b/src/main/kotlin/dev/usbharu/hideout/service/api/NoteApApiService.kt
@@ -0,0 +1,7 @@
+package dev.usbharu.hideout.service.api
+
+import dev.usbharu.hideout.domain.model.ap.Note
+
+interface NoteApApiService {
+    suspend fun getNote(postId: Long, userId: Long?): Note?
+}
diff --git a/src/main/kotlin/dev/usbharu/hideout/service/api/NoteApApiServiceImpl.kt b/src/main/kotlin/dev/usbharu/hideout/service/api/NoteApApiServiceImpl.kt
new file mode 100644
index 00000000..4fb14cfd
--- /dev/null
+++ b/src/main/kotlin/dev/usbharu/hideout/service/api/NoteApApiServiceImpl.kt
@@ -0,0 +1,37 @@
+package dev.usbharu.hideout.service.api
+
+import dev.usbharu.hideout.domain.model.ap.Note
+import dev.usbharu.hideout.domain.model.hideout.entity.Visibility
+import dev.usbharu.hideout.query.FollowerQueryService
+import dev.usbharu.hideout.query.activitypub.NoteQueryService
+import dev.usbharu.hideout.service.core.Transaction
+import org.springframework.stereotype.Service
+
+@Service
+class NoteApApiServiceImpl(
+    private val noteQueryService: NoteQueryService,
+    private val followerQueryService: FollowerQueryService,
+    private val transaction: Transaction
+) : NoteApApiService {
+    override suspend fun getNote(postId: Long, userId: Long?): Note? = transaction.transaction {
+        val findById = noteQueryService.findById(postId)
+        when (findById.second.visibility) {
+            Visibility.PUBLIC, Visibility.UNLISTED -> {
+                return@transaction findById.first
+            }
+
+            Visibility.FOLLOWERS -> {
+                if (userId == null) {
+                    return@transaction null
+                }
+
+                if (followerQueryService.alreadyFollow(findById.second.userId, userId).not()) {
+                    return@transaction null
+                }
+                return@transaction findById.first
+            }
+
+            Visibility.DIRECT -> return@transaction null
+        }
+    }
+}
diff --git a/src/main/kotlin/dev/usbharu/hideout/service/signature/HttpSignatureUser.kt b/src/main/kotlin/dev/usbharu/hideout/service/signature/HttpSignatureUser.kt
index d9c55816..ad1b1859 100644
--- a/src/main/kotlin/dev/usbharu/hideout/service/signature/HttpSignatureUser.kt
+++ b/src/main/kotlin/dev/usbharu/hideout/service/signature/HttpSignatureUser.kt
@@ -7,6 +7,7 @@ import java.io.Serial
 class HttpSignatureUser(
     username: String,
     val domain: String,
+    val id: Long,
     credentialsNonExpired: Boolean,
     accountNonLocked: Boolean,
     authorities: MutableCollection<out GrantedAuthority>?
@@ -19,6 +20,26 @@ class HttpSignatureUser(
     accountNonLocked,
     authorities
 ) {
+
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other !is HttpSignatureUser) return false
+        if (!super.equals(other)) return false
+
+        if (domain != other.domain) return false
+        if (id != other.id) return false
+
+        return true
+    }
+
+    override fun hashCode(): Int {
+        var result = super.hashCode()
+        result = 31 * result + domain.hashCode()
+        result = 31 * result + id.hashCode()
+        return result
+    }
+
     companion object {
         @Serial
         private const val serialVersionUID: Long = -3330552099960982997L
diff --git a/src/main/kotlin/dev/usbharu/hideout/service/signature/HttpSignatureUserDetailsService.kt b/src/main/kotlin/dev/usbharu/hideout/service/signature/HttpSignatureUserDetailsService.kt
index f86d7bfb..d1d619ca 100644
--- a/src/main/kotlin/dev/usbharu/hideout/service/signature/HttpSignatureUserDetailsService.kt
+++ b/src/main/kotlin/dev/usbharu/hideout/service/signature/HttpSignatureUserDetailsService.kt
@@ -49,6 +49,7 @@ class HttpSignatureUserDetailsService(
             HttpSignatureUser(
                 username = findByKeyId.name,
                 domain = findByKeyId.domain,
+                id = findByKeyId.id,
                 credentialsNonExpired = true,
                 accountNonLocked = true,
                 authorities = mutableListOf()