The present invention provides a bracket configuration for retaining a washer within a washer case which has an opening for inserting the bracket therethrough so that the washer case is mounted to the bracket from above the washer. The bracket configuration specifically includes a hole configured to dispose the washer thereon and insert a bolt therethrough, and a rib formed along an edge of the opening so as to prevent or protect the washer from deviation or disconnection via a clearance gap created between the opening and the bracket.