Provided is an automotive rear body structure which can effectively increase the torsional and bending rigidity of a rear part of the automotive body. A damper stiffener 21 is attached to an outer wall of each wheel house inner 15a so as to jointly define a closed cross section. A floor cross member 22 is attached to the outer walls of floor frames 14 and a rear floor panel 6 so as to jointly define a closed cross section. Each damper stiffener 21 extends to such an extent that its lower end overlaps with the upper end of the corresponding floor frame 14 and is spot welded to the corresponding wheel house inner 15a along with the floor cross member 22. Thereby, a closed cross section frame 23 having ridge lines 1 and 1' continually extending from the bottom wall of the trunk room 13 to each side wall thereof firmly connects the right and left wheel houses 15 and the rear floor panel 6 to the floor frames 14.
