diff --git a/src/components/card/CommentForm.vue b/src/components/card/CommentForm.vue
index 69714b66b..a530900ef 100644
--- a/src/components/card/CommentForm.vue
+++ b/src/components/card/CommentForm.vue
@@ -41,6 +41,7 @@
 					</span>
 				</template>
 				<div ref="contentEditable"
+					class="comment-form__contenteditable"
 					contenteditable
 					@keydown.enter="handleKeydown"
 					@paste="onPaste"
@@ -175,6 +176,10 @@ export default {
 <style scoped lang="scss">
 	@import '../../css/comments';
 
+	.comment-form__contenteditable {
+		word-break: break-word;
+	}
+
 	.atwho-wrap {
 		width: 100%;
 		& > div[contenteditable] {
diff --git a/src/css/comments.scss b/src/css/comments.scss
index e58da2e6a..f2fa497a2 100644
--- a/src/css/comments.scss
+++ b/src/css/comments.scss
@@ -48,4 +48,5 @@
 
 .comment--content {
 	margin-left: 44px;
+	word-break: break-word;
 }