In order to provide a rear body structure of an automobile which can arrange a spare tire in the compartment, can enhance safety for the crewmen by increasing an impact energy absorption amount at the time of collision, and can protect a fuel tank surely, the body structure of an automobile where a subframe (12) for supporting the right and left rear wheels is arranged in the rear of the right and left side sills (3, 2), includes a pair of right and left rear side frames (6,7), extending in the rear of the body from both of the side sills (3, 2), a rear floor panel (11) in-+ which a spare tire pan (10) is formed to project downward between both of the rear side frames (7, 6), and at least one rear center frame (21, 22) extending in the front and back direction along the bottom wall of thespare tire pan (10) wherein the rear center frame (21, 22) is arranged to be substantially flush with the subframe member (12) at the rear of the subframe member (12).