A rear wheel braking force control apparatus of a vehicle includes a pressure sensor (74) for detecting master cylinder pressure, right and left proportioning valves (PCV 57₁ and 57₂) individually disposed in passages for transmitting master cylinder pressure to right and left wheel cylinders of the rear wheels for controlling to decrease changes in wheel cylinder pressure relative to changes in master cylinder pressure, right and left PCV bypass valves (62) and (63) for individually bypassing the proportioning valves, and a controller (71) which, when the vehicle is determined by a steering angle sensor (77) or the like to be turning, closes the PCV bypass valve at the outer wheel side when the master cylinder pressure is higher than the pressure of the PCV bypass valve at the inner wheel side.