diff --git a/releasenotes/notes/deprecate-monasca-ds-9065f4d4bee09ab2.yaml b/releasenotes/notes/deprecate-monasca-ds-9065f4d4bee09ab2.yaml
new file mode 100644
index 000000000..bf16521ed
--- /dev/null
+++ b/releasenotes/notes/deprecate-monasca-ds-9065f4d4bee09ab2.yaml
@@ -0,0 +1,5 @@
+---
+deprecations:
+  - |
+    Monasca Data Source is deprecated and will be removed in the future, due
+    to inactivity of Monasca project.
diff --git a/watcher/decision_engine/datasources/manager.py b/watcher/decision_engine/datasources/manager.py
index 8e0959c63..e1b39d867 100644
--- a/watcher/decision_engine/datasources/manager.py
+++ b/watcher/decision_engine/datasources/manager.py
@@ -63,6 +63,9 @@ class DataSourceManager(object):
                 LOG.warning('Invalid Datasource: %s. Allowed: %s ', *msgargs)
 
         self.datasources = self.config.datasources
+        if self.datasources and mon.MonascaHelper.NAME in self.datasources:
+            LOG.warning('The monasca datasource is deprecated and will be '
+                        'removed in a future release.')
 
     @property
     def monasca(self):