diff --git a/src/test/kotlin/dev/usbharu/hideout/core/service/timeline/TimelineServiceTest.kt b/src/test/kotlin/dev/usbharu/hideout/core/service/timeline/TimelineServiceTest.kt
new file mode 100644
index 00000000..4302a2ad
--- /dev/null
+++ b/src/test/kotlin/dev/usbharu/hideout/core/service/timeline/TimelineServiceTest.kt
@@ -0,0 +1,110 @@
+package dev.usbharu.hideout.core.service.timeline
+
+import dev.usbharu.hideout.application.service.id.TwitterSnowflakeIdGenerateService
+import dev.usbharu.hideout.core.domain.model.post.Visibility
+import dev.usbharu.hideout.core.domain.model.timeline.Timeline
+import dev.usbharu.hideout.core.domain.model.timeline.TimelineRepository
+import dev.usbharu.hideout.core.domain.model.user.User
+import dev.usbharu.hideout.core.query.FollowerQueryService
+import dev.usbharu.hideout.core.query.UserQueryService
+import kotlinx.coroutines.test.runTest
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.extension.ExtendWith
+import org.mockito.ArgumentCaptor
+import org.mockito.Captor
+import org.mockito.InjectMocks
+import org.mockito.Mock
+import org.mockito.junit.jupiter.MockitoExtension
+import org.mockito.kotlin.*
+import utils.PostBuilder
+import utils.UserBuilder
+
+@ExtendWith(MockitoExtension::class)
+class TimelineServiceTest {
+
+    @Mock
+    private lateinit var followerQueryService: FollowerQueryService
+
+    @Mock
+    private lateinit var userQueryService: UserQueryService
+
+    @Mock
+    private lateinit var timelineRepository: TimelineRepository
+
+    @InjectMocks
+    private lateinit var timelineService: TimelineService
+
+    @Captor
+    private lateinit var captor: ArgumentCaptor<List<Timeline>>
+
+    @Test
+    fun `publishTimeline ローカルの投稿はローカルのフォロワーと投稿者のタイムラインに追加される`() = runTest {
+        val post = PostBuilder.of()
+        val listOf = listOf<User>(UserBuilder.localUserOf(), UserBuilder.localUserOf())
+        val localUserOf = UserBuilder.localUserOf(id = post.userId)
+
+        whenever(followerQueryService.findFollowersById(eq(post.userId))).doReturn(listOf)
+        whenever(userQueryService.findById(eq(post.userId))).doReturn(localUserOf)
+        whenever(timelineRepository.generateId()).doReturn(TwitterSnowflakeIdGenerateService.generateId())
+
+
+        timelineService.publishTimeline(post, true)
+
+        verify(timelineRepository).saveAll(capture(captor))
+        val timelineList = captor.value
+
+        assertThat(timelineList).hasSize(4).anyMatch { it.userId == post.userId }
+    }
+
+    @Test
+    fun `publishTimeline リモートの投稿はローカルのフォロワーのタイムラインに追加される`() = runTest {
+        val post = PostBuilder.of()
+        val listOf = listOf<User>(UserBuilder.localUserOf(), UserBuilder.localUserOf())
+
+        whenever(followerQueryService.findFollowersById(eq(post.userId))).doReturn(listOf)
+        whenever(timelineRepository.generateId()).doReturn(TwitterSnowflakeIdGenerateService.generateId())
+
+
+        timelineService.publishTimeline(post, false)
+
+        verify(timelineRepository).saveAll(capture(captor))
+        val timelineList = captor.value
+
+        assertThat(timelineList).hasSize(3)
+    }
+
+    @Test
+    fun `publishTimeline パブリック投稿はパブリックタイムラインにも追加される`() = runTest {
+        val post = PostBuilder.of()
+        val listOf = listOf<User>(UserBuilder.localUserOf(), UserBuilder.localUserOf())
+
+        whenever(followerQueryService.findFollowersById(eq(post.userId))).doReturn(listOf)
+        whenever(timelineRepository.generateId()).doReturn(TwitterSnowflakeIdGenerateService.generateId())
+
+
+        timelineService.publishTimeline(post, false)
+
+        verify(timelineRepository).saveAll(capture(captor))
+        val timelineList = captor.value
+
+        assertThat(timelineList).hasSize(3).anyMatch { it.userId == 0L }
+    }
+
+    @Test
+    fun `publishTimeline パブリック投稿ではない場合はローカルのフォロワーのみに追加される`() = runTest {
+        val post = PostBuilder.of(visibility = Visibility.UNLISTED)
+        val listOf = listOf<User>(UserBuilder.localUserOf(), UserBuilder.localUserOf())
+
+        whenever(followerQueryService.findFollowersById(eq(post.userId))).doReturn(listOf)
+        whenever(timelineRepository.generateId()).doReturn(TwitterSnowflakeIdGenerateService.generateId())
+
+
+        timelineService.publishTimeline(post, false)
+
+        verify(timelineRepository).saveAll(capture(captor))
+        val timelineList = captor.value
+
+        assertThat(timelineList).hasSize(2).noneMatch { it.userId == 0L }
+    }
+}