PURPOSE: To provide a reinforcing structure for the surroundings of a rear locker which improves rigidity substantially without increasing the number of part items.

CONSTITUTION: A side panel outer 11, a locker inner 12, a locker inner rear 13 are joined with one another, and a mutual overlap part S is set by extending each end 12a and 13a of the locker inner 12 and the locker inner rear 13. The locker inner rear 13 has U-shaped sections at both ends in the longitudinal direction of the overlap part S and a flat section at the center. The side panel outer 12, the locker inner 12, and locker inner rear 13 are joined en bloc along the top and bottom edges of the overlap part, and the locker inner 12 and the locker inner rear 13 are joined en bloc along both ends of the overlap part S.