diff --git a/README.rst b/README.rst
index 9c167be..98823bb 100644
--- a/README.rst
+++ b/README.rst
@@ -19,7 +19,11 @@ python bugdaystats.py output
 'output' is the name of the directory you will generate data
 and HTML files to (if they don't exist yet). It should contain a
 'js' subdirectory containing JavaScript include files, but
-otherwise be empty.
+otherwise be empty. In addition, it can contain two types of data
+files. One file contains data in each time when running the script,
+and another one is created daily. That means the creation is skipped
+if the previous data is in the same day. The data file is useful for
+showing long-term bug situation.
 
 You'll need to run the script at least twice to generate enough
 stats to get a graph.
@@ -39,3 +43,8 @@ page.
 You can also optionally specify a 'rotation' parameter. Entries older
 than the value (in days) will be removed from the dataset, resulting
 in a rolling view of bug activity.
+
+And you can also optionally specify a 'daily' parameter to enable the
+feature of daily data collection and showing its graphs.
+'daily_rotation' parameter is for daily data collection feature but
+it is same as 'rotation' parameter.
diff --git a/bugdaystats.py b/bugdaystats.py
index 0ed64d5..6d5af17 100755
--- a/bugdaystats.py
+++ b/bugdaystats.py
@@ -41,20 +41,29 @@ def create_files(templatepath, outputpath, projects):
             template.stream(project=project).dump(projectfile)
 
 
-def update_stats(outputpath, project_name, rotation):
+def update_stats(outputpath, project_name, rotation, daily=False):
 
     now = int(time.time())
     records = []
     counts = {}
     project = launchpad.projects[project_name]
-    project_stats_filename = os.path.join(outputpath,
-                                          "%s-bug-stats.json" % (project_name))
+    if daily:
+        filename = "%s-bug-stats-daily.json" % project_name
+    else:
+        filename = "%s-bug-stats.json" % project_name
+    project_stats_filename = os.path.join(outputpath, filename)
 
     try:
         data_file = open(project_stats_filename, 'r')
         json_data = json.load(data_file)
         data_file.close()
         for record in json_data['records']:
+            if daily:
+                if (now - record['date']) < (24 * 60 * 60):
+                    # Skip to update stats if the recode contains the same
+                    # day data.
+                    return
+
             if rotation:
                 if (now - record['date']) > (rotation * 24 * 60 * 60):
                     continue
@@ -159,6 +168,8 @@ if __name__ == '__main__':
         config = json.load(configfile)
     projects = config['projects']
     rotation = config.get('rotation')
+    daily = config.get('daily')
+    daily_rotation = config.get('daily_rotation')
     openstack_status = config.get('openstack_status')
 
     # Create files in output directory, if needed
@@ -170,3 +181,6 @@ if __name__ == '__main__':
 
     for p in projects:
         update_stats(outputpath, p['project'], rotation)
+
+        if (daily):
+            update_stats(outputpath, p['project'], daily_rotation, daily=True)
diff --git a/config.js.sample b/config.js.sample
index bfee5ec..0cbef66 100644
--- a/config.js.sample
+++ b/config.js.sample
@@ -10,5 +10,7 @@
         { "project": "openstack-manuals", "title": "Manuals" },
         { "project": "tempest" }
     ],
-    "rotation": 2
+    "rotation": 2,
+    "daily": true,
+    "daily_rotation": 183
 }