diff --git a/lib/fluent/plugin_helper/child_process.rb b/lib/fluent/plugin_helper/child_process.rb
index e72cb18547..738b336328 100644
--- a/lib/fluent/plugin_helper/child_process.rb
+++ b/lib/fluent/plugin_helper/child_process.rb
@@ -191,7 +191,7 @@ def close
             child_process_kill(process_info, force: true)
           end
 
-          break if living_process_exist
+          break unless living_process_exist
 
           sleep CHILD_PROCESS_LOOP_CHECK_INTERVAL
         end