diff --git a/environment.yml b/environment.yml
index 2623436e9..01ddc69a6 100644
--- a/environment.yml
+++ b/environment.yml
@@ -54,7 +54,6 @@ dependencies:
         - git+https://github.com/neocxi/prettytensor.git
         - jupyter
         - progressbar2
-        - chainer==1.18.0
         - https://storage.googleapis.com/tensorflow/linux/gpu/tensorflow_gpu-1.0.1-cp35-cp35m-linux_x86_64.whl; 'linux' in sys_platform
         - https://storage.googleapis.com/tensorflow/mac/gpu/tensorflow_gpu-1.0.1-py3-none-any.whl; sys_platform == 'darwin'
         - numpy-stl==2.2.0