You need to have the following components to use Chainer.

  • Python
    • Supported Versions: 2.7.6+, 3.5.1+, 3.6.0+ and 3.7.0+.

  • NumPy
    • Supported Versions: 1.9, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16 and 1.17.

    • NumPy will be installed automatically during the installation of Chainer.

Before installing Chainer, we recommend you to upgrade setuptools and pip:

$ pip install -U setuptools pip

Hardware Acceleration Support

You can accelerate performance of Chainer by installing the following optional components.

Optional Features

The following packages are optional dependencies. Chainer can be installed without them, in which case the corresponding features are not available.

  • Image dataset support
    • pillow 2.3+

    • Run pip install pillow to install.

  • HDF5 serialization support
    • h5py 2.5+

    • Run pip install h5py to install.

  • Distributed Deep Learning using ChainerMN

Install Chainer

Using pip

We recommend to install Chainer via pip:

$ pip install chainer


Any optional dependencies (including CuPy) can be added after installing Chainer. Chainer automatically detects the available packages and enables/disables the optional features appropriately.

Using Tarball

The tarball of the source tree is available via pip download chainer or from the release notes page. You can install Chainer from the tarball:

$ pip install chainer-x.x.x.tar.gz

You can also install the development version of Chainer from a cloned Git repository:

$ git clone
$ cd chainer
$ pip install .

Enable CUDA/cuDNN support

In order to enable CUDA support, you have to install CuPy manually. If you also want to use cuDNN, you have to install CuPy with cuDNN support. See CuPy’s installation guide to install CuPy. Once CuPy is correctly set up, Chainer will automatically enable CUDA support.

You can refer to the following flags to confirm if CUDA/cuDNN support is actually available.


True if Chainer successfully imports cupy.


True if cuDNN support is available.

Google Colaboratory

You can install Chainer and CuPy using the following snippet on Google Colaboratory:

!curl | sh -

See chainer/google-colaboratory for more details and examples.

Uninstall Chainer

Use pip to uninstall Chainer:

$ pip uninstall chainer


When you upgrade Chainer, pip sometimes install the new version without removing the old one in site-packages. In this case, pip uninstall only removes the latest one. To ensure that Chainer is completely removed, run the above command repeatedly until pip returns an error.

Upgrade Chainer

Just use pip with -U option:

$ pip install -U chainer

Reinstall Chainer

If you want to reinstall Chainer, please uninstall Chainer and then install it. We recommend to use --no-cache-dir option as pip sometimes uses cache:

$ pip uninstall chainer
$ pip install chainer --no-cache-dir

Run Chainer with Docker

We are providing the official Docker image. Use nvidia-docker command to run Chainer image with GPU. You can login to the environment with bash, and run the Python interpreter:

$ nvidia-docker run -it chainer/chainer /bin/bash

Or run the interpreter directly:

$ nvidia-docker run -it chainer/chainer /usr/bin/python


Warning message “cuDNN is not enabled” appears

You failed to build CuPy with cuDNN. If you don’t need cuDNN, ignore this message. Otherwise, retry to install CuPy with cuDNN. pip install -vvvv option helps you. There is no need of re-installing Chainer itself. See CuPy’s installation guide for more details.

CuPy always raises cupy.cuda.compiler.CompileException

See FAQ section of CuPy’s installation guide for details.

h5py installation failed

If the installation failed with error saying hdf5.h is not found, you need to install libhdf5 first. The way to install it depends on your environment:

# Ubuntu 14.04/16.04
$ apt-get install libhdf5-dev

# CentOS 7
$ yum -y install epel-release
$ yum install hdf5-devel

Note that h5py is not required unless you need HDF5 serialization support.