diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -96,6 +96,11 @@ Estimation by Unscented Kalman Filter
 ![](src/simulations/perception/sensor_auto_calibration/sensor_auto_calibration.gif)  
 
 
+## Documents
+Design documents of each Python programs are prepared here. The documents are still not completed. They have been being updated. If you found any problems in them, please tell me by creating an issue.  
+[Documents link](/doc/DESIGN_DOCUMENT.md)  
+
+
 ## License
 MIT  
 
diff --git a/doc/DESIGN_DOCUMENT.md b/doc/DESIGN_DOCUMENT.md
new file mode 100644
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@@ -0,0 +1,6 @@
+# Python programs Design Document
+This document provides an explanation of each Python programs design in this repository.  
+
+## Table of contents
+1. [World Visualization](/doc/1_world_visualization/)
+2. [Vehicle Model](/doc/2_vehicle_model/)
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