diff --git a/databricks/koalas/version.py b/databricks/koalas/version.py
index b97f8f12d5..465f887704 100644
--- a/databricks/koalas/version.py
+++ b/databricks/koalas/version.py
@@ -14,4 +14,4 @@
 # limitations under the License.
 #
 
-__version__ = '0.3.0'
+__version__ = '0.4.0'