An accelerator pedal system includes a pedal lever, a lock mechanism, an actuator, and an ECU. The pedal lever operates according to a step-on operation. The lock mechanism can restrict an operation of the pedal lever. The actuator switches between a locked state in which the operation of the pedal lever is restricted by the lock mechanism and an unlocked state in which the operation of the pedal lever is not restricted. The ECU includes a lock operation determination unit and an actuator control unit. The lock operation determination unit unlocks the pedal lever when an approaching object from behind is detected during a travel of a vehicle in the locked state.