diff --git a/src/features/core/internal/Voice/internal/Voice.class.ts b/src/features/core/internal/Voice/internal/Voice.class.ts
index 1f7b8f01..b40ebab4 100644
--- a/src/features/core/internal/Voice/internal/Voice.class.ts
+++ b/src/features/core/internal/Voice/internal/Voice.class.ts
@@ -1,7 +1,6 @@
 import type {
   VoiceConnection,
   ChatInputCommandInteraction,
-  InteractionReplyOptions,
   VoiceBasedChannel,
 } from '@/features/library/index.js';
 import {
@@ -9,6 +8,7 @@ import {
   isNil,
   joinVoiceChannel,
 } from '@/features/library/index.js';
+import { LogicException } from '@/features/others/Error/LogicException.js';
 import { getInteractionMemberId } from '@/features/others/discord/index.js';
 
 import { JOINABLE_TYPE_MAP } from './Voice.constants.js';
@@ -24,26 +24,55 @@ export class Voice {
   }: {
     interaction: Readonly<ChatInputCommandInteraction>;
   }) {
-    const member = await getInteractionMemberId(interaction);
-    const checkJoinableResult = this.checkJoinable({
-      channel: member.voice.channel,
+    const {
+      voice: { channel },
+    } = await getInteractionMemberId(interaction);
+    const joinable = this.checkJoinable({
+      channel,
     });
 
-    if (checkJoinableResult.joinableType !== JOINABLE_TYPE_MAP.JOINABLE)
-      return false;
+    switch (joinable) {
+      case JOINABLE_TYPE_MAP.NOT_FOUND:
+        interaction.reply({
+          content: '接続先のVCが見つかりません。',
+          ephemeral: false,
+        });
+        return false;
 
-    const connection = joinVoiceChannel({
-      channelId: checkJoinableResult.channel.id,
-      guildId: checkJoinableResult.channel.guild.id,
-      adapterCreator: checkJoinableResult.channel.guild.voiceAdapterCreator,
-    });
+      case JOINABLE_TYPE_MAP.NOT_JOINABLE:
+        interaction.reply({
+          content: '接続先のVCに参加できません。権限の見直しをしてください。',
+          ephemeral: true,
+        });
+        return false;
 
-    this.#connection.push({
-      guildId: checkJoinableResult.channel.guild.id,
-      connection,
-    });
+      case JOINABLE_TYPE_MAP.NOT_VIEWABLE:
+        interaction.reply({
+          content: '接続先のVCに参加できません。権限の見直しをしてください。',
+          ephemeral: true,
+        });
+        return false;
 
-    return true;
+      case JOINABLE_TYPE_MAP.JOINABLE:
+        if (isNil(channel))
+          throw new LogicException(
+            'Channel is null. Please check checkJoinable()'
+          );
+        const connection = joinVoiceChannel({
+          channelId: channel.id,
+          guildId: channel.guild.id,
+          adapterCreator: channel.guild.voiceAdapterCreator,
+        });
+
+        this.#connection.push({
+          guildId: channel.guild.id,
+          connection,
+        });
+        return true;
+
+      default:
+        throw new LogicException('Unknown joinable type.');
+    }
   }
 
   public async leave({
@@ -76,37 +105,19 @@ export class Voice {
     }
   }
 
-  checkJoinable({ channel }: { channel: VoiceBasedChannel | null }):
-    | (Pick<InteractionReplyOptions, 'content' | 'ephemeral'> & {
-        joinableType: Exclude<
-          (typeof JOINABLE_TYPE_MAP)[keyof typeof JOINABLE_TYPE_MAP],
-          typeof JOINABLE_TYPE_MAP.JOINABLE
-        >;
-      })
-    | {
-        joinableType: typeof JOINABLE_TYPE_MAP.JOINABLE;
-        channel: VoiceBasedChannel;
-      } {
+  checkJoinable({
+    channel,
+  }: {
+    channel: VoiceBasedChannel | null;
+  }): (typeof JOINABLE_TYPE_MAP)[keyof typeof JOINABLE_TYPE_MAP] {
     if (isNil(channel)) {
-      return {
-        joinableType: JOINABLE_TYPE_MAP.NOT_FOUND,
-        content: '接続先のVCが見つかりません。',
-        ephemeral: false,
-      };
+      return JOINABLE_TYPE_MAP.NOT_FOUND;
     } else if (!channel.joinable) {
-      return {
-        joinableType: JOINABLE_TYPE_MAP.NOT_JOINABLE,
-        content: '接続先のVCに参加できません。権限の見直しをしてください。',
-        ephemeral: true,
-      };
+      return JOINABLE_TYPE_MAP.NOT_JOINABLE;
     } else if (!channel.viewable) {
-      return {
-        joinableType: JOINABLE_TYPE_MAP.NOT_VIEWABLE,
-        content: '接続先のVCに参加できません。権限の見直しをしてください。',
-        ephemeral: true,
-      };
+      return JOINABLE_TYPE_MAP.NOT_VIEWABLE;
     } else {
-      return { joinableType: JOINABLE_TYPE_MAP.JOINABLE, channel };
+      return JOINABLE_TYPE_MAP.JOINABLE;
     }
   }
 }