diff --git a/Dockerfile b/Dockerfile
index 836b0f8..dcc2146 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,18 +1,5 @@
 FROM python:3.7.6-alpine3.11
 
-RUN apk add --update gnuplot \
-        fontconfig \
-        ttf-ubuntu-font-family \
-        msttcorefonts-installer \
-        curl && \
-    update-ms-fonts && \
-    fc-cache -f && \
-    rm -rf /var/cache/apk/*
-
-RUN curl -L https://github.com/sile/kurobako/releases/download/0.1.4/kurobako-0.1.4.linux-amd64 -o kurobako && \
-    chmod +x ./kurobako && \
-    ./kurobako -h
-
 RUN pip install PyGithub
 
 COPY entrypoint.sh /entrypoint.sh
diff --git a/README.md b/README.md
index 4217e6d..9a37df9 100644
--- a/README.md
+++ b/README.md
@@ -1,30 +1,28 @@
 # github-actions-kurobako
 
 GitHub Action to report [kurobako](https://github.com/sile/kurobako) benchmark results on the PR.
+See [github-actions-kurobako/plot](./plot) action to generate a plot image.
 
 ## Inputs
 
-### `report-json-path`
+### `report-md-path`
 
-**Required** File path to a json generated by kurobako run command. Default `"./kurobako.json"`.
+**Required** File path to a json generated by kurobako report command.
 
-## Outputs
-
-### `image-path`
+### `public-image-url`
 
-A file path to the generated image of kurobako.
-You need to upload this on GCS.
+**Required**  A public image url to kurobako plot image.
 
-### `public-image-url`
+## Outputs
 
-URL to kurobako plot curve image which you upload later.
+Comment to the pull request or edit if previous comment exists.
 
 ## Example usage
 
 ```yaml
 uses: c-bata/github-actions-kurobako@master
 with:
-  report-json-path: '/home/runner/kurobako-report.json'
+  report-md-path: './kurobako-report.md'
   public-image-url: 'https://storage.googleapis.com/kurobako-reports/foo.png'
 ```
 
diff --git a/action.yml b/action.yml
index 7c64e77..3180588 100644
--- a/action.yml
+++ b/action.yml
@@ -1,14 +1,14 @@
-name: 'Kurobako'
-description: 'GitHub Action to report kurobako benchmark results on the PR.'
+name: 'Kurobako Report'
+description: 'GitHub Action to comment kurobako benchmark results on the pull request.'
 inputs:
-  report-json-path:
-    description: 'File path to a json generated by kurobako run command.'
+  report-md-path:
+    description: 'File path to a json generated by kurobako report command.'
     required: true
-    default: './kurobako.json'
+    default: 'kurobako.md'
   public-image-url:
-    description: 'URL to kurobako plot curve image which you upload later.'
-    required: false
-    default: ''
+    description: 'A public image url to kurobako plot image.'
+    required: true
+    default: 'https://storage.googleapis.com/kurobako-reports/dummy.png'
 outputs:
   image-path:
     description: 'A file path to the generated image of kurobako. You need to upload this on GCS.'
@@ -16,5 +16,5 @@ runs:
   using: 'docker'
   image: 'Dockerfile'
   args:
-    - ${{ inputs.report-json-path }}
+    - ${{ inputs.report-md-path }}
     - ${{ inputs.public-image-url }}
diff --git a/plot/Dockerfile b/plot/Dockerfile
new file mode 100644
index 0000000..1a8b518
--- /dev/null
+++ b/plot/Dockerfile
@@ -0,0 +1,17 @@
+FROM alpine:3.11
+
+RUN apk add --update gnuplot \
+        fontconfig \
+        ttf-ubuntu-font-family \
+        msttcorefonts-installer \
+        curl && \
+    update-ms-fonts && \
+    fc-cache -f && \
+    rm -rf /var/cache/apk/*
+
+RUN curl -L https://github.com/sile/kurobako/releases/download/0.1.4/kurobako-0.1.4.linux-amd64 -o kurobako && \
+    chmod +x ./kurobako && \
+    ./kurobako -h
+
+COPY entrypoint.sh /entrypoint.sh
+ENTRYPOINT ["/entrypoint.sh"]
diff --git a/plot/README.md b/plot/README.md
new file mode 100644
index 0000000..a28d2df
--- /dev/null
+++ b/plot/README.md
@@ -0,0 +1,23 @@
+# kurobako-plot
+
+GitHub Action to plot a benchmark result of [kurobako](https://github.com/sile/kurobako).
+
+## Inputs
+
+### `report-json-path`
+
+**Required** File path to a json generated by kurobako run command. Default `"./kurobako.json"`.
+
+## Outputs
+
+### `image-path`
+
+A file path to the generated image of kurobako.
+
+## Example usage
+
+```yaml
+uses: c-bata/github-actions-kurobako/plot@master
+with:
+  report-json-path: '/home/runner/kurobako-report.json'
+```
diff --git a/plot/action.yml b/plot/action.yml
new file mode 100644
index 0000000..930c184
--- /dev/null
+++ b/plot/action.yml
@@ -0,0 +1,15 @@
+name: 'Kurobako Plot'
+description: 'GitHub Action to run kurobako plot curve.'
+inputs:
+  report-json-path:
+    description: 'File path to a json generated by kurobako run command.'
+    required: true
+    default: './kurobako.json'
+outputs:
+  image-path:
+    description: 'A file path to the generated image of kurobako.'
+runs:
+  using: 'docker'
+  image: 'Dockerfile'
+  args:
+    - ${{ inputs.report-json-path }}
diff --git a/plot/entrypoint.sh b/plot/entrypoint.sh
new file mode 100755
index 0000000..f10017f
--- /dev/null
+++ b/plot/entrypoint.sh
@@ -0,0 +1,9 @@
+#!/bin/sh -l
+
+set -e
+
+cat $1 | ./kurobako plot curve -o ./output/
+
+imagepath=$(ls ./output/*.png | head -1)
+
+echo ::set-output name=image-path::$imagepath
diff --git a/report.py b/report.py
index 5b54520..508394f 100644
--- a/report.py
+++ b/report.py
@@ -1,12 +1,9 @@
 import json
 import os
 import sys
-import subprocess
 
 from github import Github
 
-KUROBAKO = os.getenv('KUROBAKO', './kurobako')
-OUTPUT_DIR = os.getenv('OUTPUT_DIR', './output/')
 ACCESS_TOKEN = os.getenv('GITHUB_TOKEN')
 
 
@@ -16,21 +13,13 @@ def get_webhook_event():
         return json.load(f)
 
 
-def get_kurobako_image_path():
-    # TODO(c-bata): specify output filename in the option at kurobako plot curve command.
-    # It seems kurobako accepts multiple studies, so it seems to need more discussions.
-    for filepath in os.listdir(OUTPUT_DIR):
-        if filepath.endswith('.png'):
-            return os.path.join(OUTPUT_DIR, filepath)
-    raise Exception('kurobako image not found.')
-
-
 def generate_report(kurobako_report, public_image_url):
-    metadata, detail = kurobako_report[len('# Benchmark Result Report\n\n'):].split('## Table of Contents')[:2]
+    header_trimmed = kurobako_report[len('# Benchmark Result Report\n\n'):]
+    metadata, detail = header_trimmed.split('## Table of Contents\n')[:2]
     body = f"""
 # Kurobako Benchmark
 
-{f'![plot curve image]({public_image_url})' if public_image_url else ''}
+![plot curve image]({public_image_url})
 
 {metadata}
 
@@ -38,7 +27,6 @@ def generate_report(kurobako_report, public_image_url):
 <summary>See details of benchmark results</summary>
 
 ## Table of Contents
-
 {detail}
 
 </details>
@@ -48,25 +36,18 @@ def generate_report(kurobako_report, public_image_url):
 
 def main():
     print(sys.argv)
-    json_path = sys.argv[1]
-    public_image_url = sys.argv[2] if len(sys.argv) > 2 else ''
+    markdown_report_path = sys.argv[1]
+    public_image_url = sys.argv[2]
 
     event = get_webhook_event()
     pull_number = event.get('number')
     print("Pull Request:", pull_number)
+
     repository = event.get('repository').get("full_name")
     print("Repository:", pull_number)
 
-    # Plot curve
-    subprocess.run([
-        "sh", "-c", f"cat {json_path} | {KUROBAKO} plot curve -o {OUTPUT_DIR}",
-    ], check=True)
-    print(f"::set-output name=image-path::{get_kurobako_image_path()}")
-
-    # Generate markdown report
-    kurobako_report = subprocess.check_output([
-        "sh", "-c", f"cat {json_path} | {KUROBAKO} report",
-    ], text=True)
+    with open(markdown_report_path, 'r') as f:
+        kurobako_report = f.read()
 
     client = Github(ACCESS_TOKEN)
     issue = client.get_repo(repository).get_issue(pull_number)