To provide a body rear portion structure of an automobile that can distribute load effectively to the entire body when shock load is applied from a side portion or a rear portion of the vehicle and that can assure the rigidity of the vehicle body.

This structure includes rear side frames 3 and 4, C pillars 11 and 12, D pillars 13 and 14 and a cross member 20 crossed over the frames 3 and 4, which cross member 20 having a substantially X shape when seen two-dimensionally and including a first cross member 21 where a front end 21a is connected to the rear side frame 3 in the vicinity of the C pillar 11 and a rear end 21a is connected to the rear side frame 4 in the vicinity of the D pillar 14, and a second cross member 22 where a front end 22a is connected to the rear side frame 4 in the vicinity of the C pillar 12 and crossed with the first cross member 21, and a rear end 22b is connected to the rear side frame 3 in the vicinity of the D pillar 13.