A vehicle side door internally includes an impact beam which extends along a longitudinal axis of a door. The impact beam is attached to a door inner panel via an outer extension. An inner extension is attached inside the outer extension. A distance along thickness of the door between the inner extension and the impact beam is shorter in a close proximity section than in a longitudinally neighboring area. Because the load received by the inner extension via the close proximity section is transferred to joint portions connecting to the outer extension, the load received by the outer extension from the impact beam is dispersed.