diff --git a/client/src/components/LiveOverlay/Nico.vue b/client/src/components/LiveOverlay/Nico.vue
index effb4b2..d8dfcf6 100644
--- a/client/src/components/LiveOverlay/Nico.vue
+++ b/client/src/components/LiveOverlay/Nico.vue
@@ -6,7 +6,7 @@
 import { defineComponent, ref } from 'vue'
 import { connectTarget } from '/@/lib/connect'
 import useElementSize from '/@/use/elementSize'
-import { addComment } from './commentRenderer'
+import { useCommentRenderer } from './commentRenderer'
 import { addReaction } from './reactionRenderer'
 
 export default defineComponent({
@@ -20,6 +20,7 @@ export default defineComponent({
   setup() {
     const baseEle = ref<HTMLDivElement>()
     const { height: baseHeight, width: baseWidth } = useElementSize(baseEle)
+    const { addComment } = useCommentRenderer(baseEle, baseHeight)
 
     connectTarget.addEventListener('reaction', e => {
       if (document.visibilityState === 'hidden') return
@@ -29,7 +30,7 @@ export default defineComponent({
     connectTarget.addEventListener('comment', e => {
       if (document.visibilityState === 'hidden') return
 
-      addComment(baseEle, baseHeight, e.detail.text)
+      addComment(e.detail.text)
     })
 
     return { baseEle }
diff --git a/client/src/components/LiveOverlay/commentRenderer.ts b/client/src/components/LiveOverlay/commentRenderer.ts
index 7d78c3c..233d47e 100644
--- a/client/src/components/LiveOverlay/commentRenderer.ts
+++ b/client/src/components/LiveOverlay/commentRenderer.ts
@@ -1,38 +1,59 @@
-import { Ref } from 'vue'
+import { computed, ref, Ref } from 'vue'
+
+/*
+- フォントサイズ: 画面に CommentLines 行表示できるサイズ。ただし、最低でも MinimumFontSize px
+- コメント表示位置: 上から詰める
+  - 現状、コメントはその文字長に関わらず画面内にいる間行を専有する(ニコニコでは文字列幅だけ専有している)
+*/
 
 const CommentLines = 10
-let commentLineNow = 0
+const MinimumFontSize = 20
+const LineHeight = 1.5
 
-const incrementCommentLine = () => {
-  commentLineNow++
-  if (commentLineNow === CommentLines) {
-    commentLineNow = 0
-  }
+const indexOfMin = (arr: number[]): number => {
+  const minCount = Math.min(...arr)
+  return arr.findIndex(o => o === minCount)
 }
 
-export const addComment = (
+export const useCommentRenderer = (
   baseEle: Ref<HTMLDivElement | undefined>,
-  baseHeight: Ref<number>,
-  text: string
-): void => {
-  if (!baseEle.value) return
-
-  const lineHeight = baseHeight.value / CommentLines
-
-  const $comment = document.createElement('div')
-  $comment.className = 'animation-comment'
-  $comment.textContent = text
-  $comment.style.top = `${commentLineNow * lineHeight}px`
-  $comment.style.fontSize = `${lineHeight}px`
-
-  $comment.addEventListener(
-    'animationend',
-    () => {
-      $comment.remove()
-    },
-    { once: true }
+  baseHeight: Ref<number>
+): { addComment: (text: string) => void } => {
+  const countPerLineAll = ref(Array(CommentLines).fill(0)) // 行ごとのコメント数(画面外の行を含む)
+
+  const lineCount = computed(() =>
+    Math.min(
+      Math.floor(baseHeight.value / (MinimumFontSize * LineHeight)),
+      CommentLines
+    )
   )
-  baseEle.value.append($comment)
+  const lineHeight = computed(() => baseHeight.value / lineCount.value)
+  const fontSize = computed(() => lineHeight.value / LineHeight)
+
+  const addComment = (text: string) => {
+    if (!baseEle.value) return
 
-  incrementCommentLine()
+    const linesInScreen = countPerLineAll.value.slice(0, lineCount.value)
+    const index = indexOfMin(linesInScreen)
+    const top = index * lineHeight.value
+
+    countPerLineAll.value[index]++
+
+    const $comment = document.createElement('div')
+    $comment.className = 'animation-comment'
+    $comment.textContent = text
+    $comment.style.top = `${top}px`
+    $comment.style.fontSize = `${fontSize.value}px`
+
+    $comment.addEventListener(
+      'animationend',
+      () => {
+        $comment.remove()
+        countPerLineAll.value[index]--
+      },
+      { once: true }
+    )
+    baseEle.value.append($comment)
+  }
+  return { addComment }
 }