A steering angular velocity computing device detects a change in a steering angle, measures a required time from a time when the steering angle changed until a time when the steering angle next changed, and computes, after the detector has detected a change in the steering angle, the steering angular velocity by dividing an amount of change in the steering angle by the required time corresponding to the amount of change and outputs it. When the steering angular velocity is being reduced, the steering angular velocity computing unit outputs the steering angular velocity during a first extended output period longer than the required period. Thus, the steering angular velocity is outputted with a high accuracy when the steering angular velocity is being reduced.