diff --git a/README.md b/README.md
index 4a0bdf2..d22558c 100644
--- a/README.md
+++ b/README.md
@@ -33,9 +33,11 @@ jobs:
           GIPHY_API_KEY: ${{ secrets.GIPHY_API_KEY }}
           GITHUB_REPOSITORY: ${{ github.repository }}
           GITHUB_COMMENT_BODY: ${{ github.event.comment.body }}
+          GITHUB_COMMENT_ID: ${{ github.event.comment.id }} # not necessary if `override` is false
           GITHUB_ISSUE_NUMBER: ${{ github.event.issue.number }}
         with:
-          trigger: 'looks good to me' # default: lgtm
+          trigger: 'looks good to me' # default: 'lgtm'
+          override: true # default: false
 ```
 
 ## License
diff --git a/action.yml b/action.yml
index f07a767..c0627a1 100644
--- a/action.yml
+++ b/action.yml
@@ -6,6 +6,10 @@ inputs:
     description: 'Trigger comment on issue to send reaction'
     required: false
     default: 'lgtm'
+  overide:
+    description: 'Whether the original comment is overridden'
+    required: false
+    default: false
 runs:
   using: 'docker'
   image: 'Dockerfile'
diff --git a/cmd/action-lgtm-reaction/main.go b/cmd/action-lgtm-reaction/main.go
index c8efeda..f450cbf 100644
--- a/cmd/action-lgtm-reaction/main.go
+++ b/cmd/action-lgtm-reaction/main.go
@@ -13,56 +13,78 @@ import (
 	"github.com/micnncim/action-lgtm-reaction/pkg/github"
 )
 
+var (
+	githubToken       = os.Getenv("GITHUB_TOKEN")
+	giphyAPIKey       = os.Getenv("GIPHY_API_KEY")
+	githubRepository  = os.Getenv("GITHUB_REPOSITORY")
+	githubCommentBody = os.Getenv("GITHUB_COMMENT_BODY")
+	githubCommentID   = os.Getenv("GITHUB_COMMENT_ID")
+	githubIssueNumber = os.Getenv("GITHUB_ISSUE_NUMBER")
+	trigger           = os.Getenv("INPUT_TRIGGER")
+	override          = os.Getenv("INPUT_OVERRIDE")
+)
+
 func main() {
-	trigger := os.Getenv("INPUT_TRIGGER")
-	givenComment := os.Getenv("GITHUB_COMMENT_BODY")
-	if strings.ToUpper(trigger) != strings.ToUpper(givenComment) {
+	if strings.ToUpper(trigger) != strings.ToUpper(githubCommentBody) {
 		fmt.Fprintf(os.Stderr, "no match issue comment\n")
 		return
 	}
 
-	apiKey := os.Getenv("GIPHY_API_KEY")
-	giphyClient, err := giphy.NewClient(apiKey)
+	giphyClient, err := giphy.NewClient(giphyAPIKey)
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "unable to create giphy client: %v\n", err)
-		os.Exit(1)
+		exit("unable to create giphy client: %v\n", err)
 	}
 	giphies, err := giphyClient.Search("lgtm")
 	if err != nil {
-		os.Exit(1)
+		exit("unable to search giphy :%v\n", err)
 	}
 	if len(giphies) == 0 {
-		fmt.Fprintf(os.Stderr, "no giphy contents found\n")
-		os.Exit(1)
+		exit("no giphy contents found\n")
 	}
 
-	token := os.Getenv("GITHUB_TOKEN")
-	githubClient, err := github.NewClient(token)
+	githubClient, err := github.NewClient(githubToken)
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "unable to create github client: %v\n", err)
-		os.Exit(1)
+		exit("unable to create github client: %v\n", err)
 	}
 
-	repository := os.Getenv("GITHUB_REPOSITORY")
-	slugs := strings.Split(repository, "/")
+	slugs := strings.Split(githubRepository, "/")
 	if len(slugs) != 2 {
-		fmt.Fprintf(os.Stderr, "invalid repository: %v\n", repository)
-		os.Exit(1)
+		exit("invalid githubRepository: %v\n", githubRepository)
 	}
 	owner, repo := slugs[0], slugs[1]
-	issueNumber := os.Getenv("GITHUB_ISSUE_NUMBER")
-	number, err := strconv.Atoi(issueNumber)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "unable to convert string to int in issue number\n")
-		os.Exit(1)
-	}
-	ctx := context.Background()
 
 	rand.Seed(time.Now().Unix())
 	index := rand.Intn(len(giphies))
 	comment := giphies[index].GIFURLInMarkdownStyle()
 
+	needUpdate, err := strconv.ParseBool(override)
+	if err != nil {
+		exit("unable to parse string to bool in override flag: %v\n", err)
+	}
+
+	ctx := context.Background()
+
+	if needUpdate {
+		commentID, err := strconv.ParseInt(githubCommentID, 10, 64)
+		if err != nil {
+			exit("unable to convert string to int in issue number: %v\n", err)
+		}
+		if err := githubClient.UpdateIssueComment(ctx, owner, repo, int(commentID), comment); err != nil {
+			exit("unable to update issue comment: %v\n", err)
+		}
+		return
+	}
+
+	number, err := strconv.Atoi(githubIssueNumber)
+	if err != nil {
+		exit("unable to convert string to int in issue number: %v\n", err)
+	}
 	if err := githubClient.CreateIssueComment(ctx, owner, repo, number, comment); err != nil {
 		os.Exit(1)
 	}
 }
+
+func exit(format string, a ...interface{}) {
+	fmt.Fprintf(os.Stderr, format, a...)
+	os.Exit(1)
+}
diff --git a/pkg/github/github.go b/pkg/github/github.go
index a69e769..c946481 100644
--- a/pkg/github/github.go
+++ b/pkg/github/github.go
@@ -43,7 +43,25 @@ func (c *Client) CreateIssueComment(ctx context.Context, owner, repo string, num
 		Body: pointer.String(body),
 	})
 	if err != nil {
-		log.Error("unable to create issue", zap.Error(err))
+		log.Error("unable to create issue comment", zap.Error(err))
+		return err
+	}
+	return nil
+}
+
+func (c *Client) UpdateIssueComment(ctx context.Context, owner, repo string, commentID int, body string) error {
+	log := c.log.With(
+		zap.String("owner", owner),
+		zap.String("repo", repo),
+		zap.Int("commentID", commentID),
+		zap.String("body", body),
+	)
+
+	_, _, err := c.githubClient.Issues.EditComment(ctx, owner, repo, int64(commentID), &github.IssueComment{
+		Body: pointer.String(body),
+	})
+	if err != nil {
+		log.Error("unable to update issue comment", zap.Error(err))
 		return err
 	}
 	return nil