diff --git a/digdag-docs/src/operators/require.md b/digdag-docs/src/operators/require.md
index a78f8b9794..fb9f576108 100644
--- a/digdag-docs/src/operators/require.md
+++ b/digdag-docs/src/operators/require.md
@@ -73,6 +73,7 @@
 * **rerun_on**: none, failed, all (default: none)
 
   *rerun_on* control require> really kicks or not if the attempt for the dependent workflow already exists. 
+  If the attempt does not exist, the dependent workflow is always kicked.
   * *none* ... Not kick the workflow if the attempt already exists.
   * *failed* ... Kick the workflow if the attempt exists and its result is not success.
   * *all* ... require> kick the workflow regardless of the result of the attempt.