A rear subframe structure is provided with a rear subframe configured such that a front cross member, a rear cross member, a pair of left and right upper side members, and a pair of left and right lower side members are connected; and a vehicle-body mounting portion formed on each of both ends of the front cross member, and on each of rear ends of the upper side members. The rear subframe further includes a pillar portion formed between the upper side member and the lower side member; a first-arm support portion formed on the pillar portion to support a first arm; a second-arm support portion formed on the pillar portion to support a second arm; and an arm support bracket to support the second-arm support portion from a rear side.