An impact bar includes a U-shaped portion formed by a vertical face portion and upper-and-lower lateral face portions at its front end. The impact bar further includes upper-and-lower outer face portions. A pair of first joint portions which are formed so as to extend upward and downward from respective front ends of the upper-and-lower lateral face portions are joined to a lateral face portion of a door inner panel. A pair of second joint portions which are formed so as to extend forward from respective front ends of the upper-and-lower outer face portions are joined to a longitudinal face portion of the door inner panel.