A bracket is fixed to a door beam which is fixed to an inner panel between the inner panel and an outer panel of the door. The bracket extends from the door beam toward the outer panel and includes at an end thereof a curved part protruding toward the outer panel. The bracket is connected at the end thereof to the outer panel through the vibration damping member. The bracket has a predetermined length and is fixed to the inner panel at an angle between the inner panel reference plane and the extending direction. The angle is determined on the basis of a distance between the door beam and the outer panel.