diff --git a/android/app/src/main/java/com/now/naaga/presentation/onadventure/OnAdventureActivity.kt b/android/app/src/main/java/com/now/naaga/presentation/onadventure/OnAdventureActivity.kt
index 95acee13e..83b59aa89 100644
--- a/android/app/src/main/java/com/now/naaga/presentation/onadventure/OnAdventureActivity.kt
+++ b/android/app/src/main/java/com/now/naaga/presentation/onadventure/OnAdventureActivity.kt
@@ -103,7 +103,7 @@ class OnAdventureActivity :
             viewModel.endAdventure()
         }
         binding.ivSendLetter.setOnClickListener {
-            LetterSendDialog(viewModel::sendLetter).show(supportFragmentManager, LetterSendDialog.TAG)
+            LetterSendDialog(::registerLetter).show(supportFragmentManager, LetterSendDialog.TAG)
         }
     }
 
@@ -203,6 +203,14 @@ class OnAdventureActivity :
         }
     }
 
+    private fun registerLetter(message: String) {
+        if (message.isNotEmpty()) {
+            viewModel.sendLetter(message)
+        } else {
+            showToast(getString(R.string.send_letter_dialog_warning))
+        }
+    }
+
     private fun showGiveUpDialog() {
         val fragment: Fragment? = supportFragmentManager.findFragmentByTag(GIVE_UP)
         if (fragment == null) {
diff --git a/android/app/src/main/res/values/strings.xml b/android/app/src/main/res/values/strings.xml
index 24a77863a..13fb026cb 100644
--- a/android/app/src/main/res/values/strings.xml
+++ b/android/app/src/main/res/values/strings.xml
@@ -146,6 +146,7 @@
 
     <!-- SendLetterDialog -->
     <string name="send_letter_dialog_hint">이 곳에 내용을 작성해주세요!</string>
+    <string name="send_letter_dialog_warning">내용을 1자 이상 입력해주세요!</string>
     <string name="send_letter_dialog_submit">전송하기</string>
 
     <!-- All -->