A device (1) for estimating the state of a driver comprises a steering angle sensor (2) for detecting the steering angle of a steering wheel, a steering torque sensor (3) for detecting steering torque applied to the steering wheel, and an ECU (4) having a steering angle estimating section (5) and a driver state estimating section (6). After inputs of both a steering angle (detected steering angle value) (MA) detected by the steering angle sensor (2) and steering torque (detected steering torque value) (MT) detected by the steering torque sensor (3), the steering angle estimating section (5) determines whether or not the detected steering angle value (MA) is 0. If the detected steering angle value (MA) is 0, the steering angle estimating section (5) calculates an estimated steering angle value (MAest) by multiplying the detected steering torque value (MT) by the gradient (proportional coefficient) alpha of the steering angle relative to the steering torque, and if not, the steering angle estimating section (5) determines the detected steering angle value (MA) to be the estimated steering angle value (MAest).
Device for estimating state of driver