An awake state estimation portion calculates an average steering angle, an average steering angular speed and a corrective steering angle on the basis of the steering angle acquired from a steering angle detection portion. The awake state estimation portion acquires the traveling speed of the vehicle from a vehicle speed detection portion. The awake state estimation portion corrects the calculated corrective steering angle by a correction value commensurate with the type of the traveling path on which the vehicle is traveling, and estimates the degree of the awake state of the driver on the basis of the post-correction corrective steering angle. Besides, the awake state estimation portion specifically determines the correction value commensurate with the type of the traveling path on which the vehicle is traveling, on the basis of at least one of the steering angle, the average steering angular speed and the traveling speed.