It is an object of the present invention to increase the rigidity of a seat surface portion, to which a seat for a suspension spring is attached, of a rear side member in a vehicle body rear part. The present invention is characterized by a rear vehicle body structure in which at least intermediate portions of a pair of right and left rear side members are connected to each other by a cross member, and the seat surface portion for the suspension spring is provided on the rear side member, wherein a reinforcing panel for connecting the rear side member to the cross member is provided in a connecting portion between the rear side member and the cross member; the rear end position of the reinforcing panel is set at a substantially middle position between the connecting portion between the rear side member and the cross member and the rear end of the rear side member; and the seat surface portion for the suspension spring is set at a substantially middle position between the connecting portion between the rear side member and the cross member and the rear end of the reinforcing panel.