Patent ID: 8838340

Claim:
An electric power steering system comprising an electronic control unit configured to determine a steering state of a steering wheel based on at least one of detected values of current and voltage of a motor that applies assist force to a steering system, and a steering speed of the steering wheel, wherein a state where the steering wheel is retained at a position other than a neutral position is a retained state, and a state where the steering wheel is placed at the neutral position is a neutral state, when the steering speed is lower than a determination value and the detected value is larger than a reference value, it is determined whether the steering state of the steering wheel is the neutral state, and when the steering speed is lower than the determination value, the detected value is larger than the reference value, and it is determined that the steering state of the steering wheel is the neutral state at a time of immediately preceding determination, it is determined that the steering state of the steering wheel is the neutral state.