diff --git a/CITATION.cff b/CITATION.cff
index e0469a5..ceed1ac 100644
--- a/CITATION.cff
+++ b/CITATION.cff
@@ -28,4 +28,4 @@ message: "If you use this software, please cite it using these metadata."
 repository-code: "https://github.com/inab/WfExS-backend"
 type: software
 title: "WfExS-backend"
-version: 1.0.0a0
+version: 1.0.0a1
diff --git a/wfexs_backend/__init__.py b/wfexs_backend/__init__.py
index 5f73692..ff4e1f2 100644
--- a/wfexs_backend/__init__.py
+++ b/wfexs_backend/__init__.py
@@ -21,7 +21,7 @@
 __license__ = "Apache 2.0"
 
 # https://www.python.org/dev/peps/pep-0396/
-__version__ = "1.0.0a0"
+__version__ = "1.0.0a1"
 __url__ = "https://github.com/inab/WfExS-backend"
 __official_name__ = "WfExS-backend"