diff --git a/docs/project_structure.md b/docs/project_structure.md
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index 00000000..14efc446
--- /dev/null
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@@ -0,0 +1,71 @@
+# Project Structure
+
+In doccano v1.x, the application consists of a frontend and backend API. They are stored in the `frontend` and `app` directories.
+
+```bash
+.
+├── app
+├── docker-compose.dev.yml
+├── docker-compose.prod.yml
+├── frontend
+├── nginx
+└── tools
+```
+
+The other important files/directories are as follows:
+
+- [docker-compose.dev.yml](https://github.com/doccano/doccano/blob/master/docker-compose.dev.yml)
+- [docker-compose.prod.yml](https://github.com/doccano/doccano/blob/master/docker-compose.prod.yml)
+- [nginx](https://github.com/doccano/doccano/tree/master/nginx)
+- [tools](https://github.com/doccano/doccano/tree/master/tools)
+
+**[docker-compose.dev.yml](https://github.com/doccano/doccano/blob/master/docker-compose.dev.yml)**
+
+The `docker-compose.dev.yml` file contains configuration to run a development environment. Once we run the command `docker-compose -f docker-compose.dev.yml up`, compose runs backend API and frontend development containers.
+
+**[docker-compose.prod.yml](https://github.com/doccano/doccano/blob/master/docker-compose.prod.yml)**
+
+The `docker-compose.prod.yml` file contains configuration to run a production environment. We adopted the three tier architecture. Once we run the command `docker-compose -f docker-compose.prod.yml up`, compose builds frontend and runs DBMS, backend API and web server containers.
+
+**[nginx](https://github.com/doccano/doccano/tree/master/nginx)**
+
+The `nginx` directory contains a nginx configuration file and Docker container. They are used only in `docker-compose.prod.yml`.
+
+**[tools](https://github.com/doccano/doccano/tree/master/tools)**
+
+The `tools` directory contains some shell scripts. They are used for CI, CD and so on.
+
+## Frontend
+
+The directory structure of the frontend follows Nuxt.js one. See the Nuxt.js documentation for details:
+
+- [Nuxt.js/Directory Structure](https://nuxtjs.org/guide/directory-structure/)
+
+
+## Backend API
+
+The directory structure of the backend api follows Django one. The important directories are as follows:
+
+```bash
+.
+├── api
+├── app
+├── authentification
+└── server
+```
+
+**[app/api](https://github.com/doccano/doccano/tree/master/app/api)**
+
+The `api` directory contains backend API application. We use Django Rest Framework to implement the API. If you want to add new API, change the contents of this directory.
+
+**[app/app](https://github.com/doccano/doccano/tree/master/app/app)**
+
+The `app` directory contains Django project settings. See [Writing your first Django app, part 1](https://docs.djangoproject.com/en/3.0/intro/tutorial01/#creating-a-project).
+
+**[app/authentification](https://github.com/doccano/doccano/tree/master/app/authentification)**
+
+The `authentification` directory contains authentification application. It is mainly used for user signup.
+
+**[app/server](https://github.com/doccano/doccano/tree/master/app/server)**
+
+The `server` directory contains doccano v0.x codes. In the future, this directory will be integrated into the `api` directory.
diff --git a/mkdocs.yml b/mkdocs.yml
index 902c1d9e..d19f97b4 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -30,6 +30,7 @@ nav:
   - Doccano: index.md
   - Getting started: getting-started.md
   - Tutorial: tutorial.md
+  - Project Structure: project_structure.md
   - Advanced:
     - AWS HTTPS settings: advanced/aws_https_settings.md
     - OAuth2 settings: advanced/oauth2_settings.md