An outer door panel 2 defines a lower edge of a door window portion 8. An outer waist reinforcement 4 is disposed along the lower edge of the door window portion 8 on the inner side, in a vehicle-width direction, of the outer door panel 2, and fixed onto the inner side surface, in the vehicle-width direction, of the outer door panel 2. A door beam 5 is disposed in a front-rear direction below the outer waist reinforcement 4, and fixed onto the inner side surface, in the vehicle-width direction, of the outer door panel 2. A mirror-support stay is disposed on the outer side, in the vehicle-width direction, of the outer door panel 2, and supports a mirror. A mirror mounting member 30 is fixed to a front end portion of the outer waist reinforcement 4 and a front end portion of the door beam 5 while straddling these two front end portions to connect the two, and supports a lower end of the mirror-support stay.