A steering determination device determines a steering state in which a driver of a vehicle is steering a steering wheel of the vehicle. The device includes a torque recognition unit configured to recognize a steering torque based on a measurement result of a torque sensor provided on a steering shaft, an acceleration recognition unit configured to recognize longitudinal acceleration or lateral acceleration, a threshold value setting unit configured to set a threshold value for the determination of the steering state, based on the longitudinal acceleration or the lateral acceleration, and a steering determination unit configured to determine that the driver is in the steering state if the steering torque is equal to or greater than the threshold value. The threshold value setting unit is configured to set the threshold value such that the threshold value decreases as an absolute value of the longitudinal acceleration or the lateral acceleration decreases.