diff --git a/doc/source/configuration.rst b/doc/source/configuration.rst
index f65382d1..265ee1e1 100644
--- a/doc/source/configuration.rst
+++ b/doc/source/configuration.rst
@@ -6,4 +6,5 @@ Configuration
    :maxdepth: 2
 
    tls.rst
+   gui.rst
 
diff --git a/doc/source/gui.png b/doc/source/gui.png
new file mode 100644
index 00000000..4e5cb8c6
Binary files /dev/null and b/doc/source/gui.png differ
diff --git a/doc/source/gui.rst b/doc/source/gui.rst
new file mode 100644
index 00000000..e51d7840
--- /dev/null
+++ b/doc/source/gui.rst
@@ -0,0 +1,33 @@
+***************
+Topology Viewer
+***************
+
+ryu.app.gui_topology.gui_topology provides topology visualization.
+
+This depends on following ryu applications.
+
+===================== =================================================
+ryu.app.rest_topology Get node and link data.
+ryu.app.ws_topology   Being notified change of link up/down.
+ryu.app.ofctl_rest    Get flows of datapaths.
+===================== =================================================
+
+Usage
+=====
+
+Run mininet (or join your real environment)::
+
+    $ sudo mn --controller remote --topo tree,depth=3
+
+Run GUI application::
+
+    $ PYTHONPATH=. ./bin/ryu run --observe-links ryu/app/gui_topology/gui_topology.py
+
+Access http://<ip address of ryu host>:8080 with your web browser.
+
+Screenshot
+==========
+
+.. image:: gui.png
+   :width: 640 px
+