A rear wheel toe angle control device that ensures a stable steering performance even when the cornering powers of laterally opposing rear wheels are different from each other. When a reduction in the cornering power of one of the rear wheels owing to a drop in the tire pressure or a temporary tire is determined, a control unit changes the toe angle of the other rear wheel in a direction to increase the slip angle of thereof, and additionally changes the toe angle of the one rear wheel in a direction to decrease the slip angle of thereof. The combined cornering power of the two rear wheels is maintained at a normal level, and the steering performance of the turning vehicle remains the same. This also contributes to a stable running performance of the vehicle, and a maximization of the total available cornering power of the rear wheels.