To efficiently transmit the rigidity of a rear suspension mount section and a load produced in the event of a rear end collision, from a rear frame to a front floor frame, and to reduce the weight of a rear part of a vehicle body.

A vehicle-body rear structure includes: the front floor frame 17 extending in the longitudinal direction of the vehicle body and disposed at a central part thereof; the rear frame 12 extending from behind side sills 11 to the rear of the vehicle body; and the suspension mount section 19 disposed in front of the rear frame 12 to mount a rear suspension 23. The structure is also provided with an auxiliary member 25 with its front end connected to a lower surface 17a of the front floor frame and its rear end connected to the suspension mount section 19, wherein the auxiliary member 25 is formed of a round sectional pipe and its front portion is provided with a flattened part 32 whose upper surface position is flattened and whose lower surface portion is recessed at the center along the axis of the pipe.