diff --git a/src/main/kotlin/dev/usbharu/hideout/activitypub/domain/model/Note.kt b/src/main/kotlin/dev/usbharu/hideout/activitypub/domain/model/Note.kt
index ddca1d67..cc891c08 100644
--- a/src/main/kotlin/dev/usbharu/hideout/activitypub/domain/model/Note.kt
+++ b/src/main/kotlin/dev/usbharu/hideout/activitypub/domain/model/Note.kt
@@ -3,10 +3,10 @@ package dev.usbharu.hideout.activitypub.domain.model
 import dev.usbharu.hideout.activitypub.domain.model.objects.Object
 
 open class Note : Object {
-    var attributedTo: String? = null
+    lateinit var attributedTo: String
     var attachment: List<Document> = emptyList()
-    var content: String? = null
-    var published: String? = null
+    lateinit var content: String
+    lateinit var published: String
     var to: List<String> = emptyList()
     var cc: List<String> = emptyList()
     var sensitive: Boolean = false
@@ -19,9 +19,9 @@ open class Note : Object {
         type: List<String> = emptyList(),
         name: String,
         id: String?,
-        attributedTo: String?,
-        content: String?,
-        published: String?,
+        attributedTo: String,
+        content: String,
+        published: String,
         to: List<String> = emptyList(),
         cc: List<String> = emptyList(),
         sensitive: Boolean = false,
diff --git a/src/main/kotlin/dev/usbharu/hideout/activitypub/service/objects/note/APNoteService.kt b/src/main/kotlin/dev/usbharu/hideout/activitypub/service/objects/note/APNoteService.kt
index f7300314..28bf7c01 100644
--- a/src/main/kotlin/dev/usbharu/hideout/activitypub/service/objects/note/APNoteService.kt
+++ b/src/main/kotlin/dev/usbharu/hideout/activitypub/service/objects/note/APNoteService.kt
@@ -1,7 +1,6 @@
 package dev.usbharu.hideout.activitypub.service.objects.note
 
 import dev.usbharu.hideout.activitypub.domain.exception.FailedToGetActivityPubResourceException
-import dev.usbharu.hideout.activitypub.domain.exception.IllegalActivityPubObjectException
 import dev.usbharu.hideout.activitypub.domain.model.Note
 import dev.usbharu.hideout.activitypub.query.NoteQueryService
 import dev.usbharu.hideout.activitypub.service.common.APResourceResolveService
@@ -99,7 +98,7 @@ class APNoteServiceImpl(
 
     private suspend fun saveNote(note: Note, targetActor: String?, url: String): Note {
         val person = apUserService.fetchPersonWithEntity(
-            note.attributedTo ?: throw IllegalActivityPubObjectException("note.attributedTo is null"),
+            note.attributedTo,
             targetActor
         )
 
@@ -142,7 +141,7 @@ class APNoteServiceImpl(
             postBuilder.of(
                 id = postRepository.generateId(),
                 userId = person.second.id,
-                text = note.content.orEmpty(),
+                text = note.content,
                 createdAt = Instant.parse(note.published).toEpochMilli(),
                 visibility = visibility,
                 url = note.id ?: url,