An accelerator pedal rotates a pedal rotor when depressed. Rotors located on both sides of the pedal rotor are relatively rotatable to the pedal rotor. Second helical teeth of the rotors project toward the pedal rotor and engage with first helical teeth of the pedal rotor to bias the rotors when the pedal rotor rotates in the accelerator opening direction. The pedal rotor is rotatable to an accelerator full-close position without interfering with the first helical teeth when the pedal rotor rotates in an accelerator closing direction. A first biasing unit biases the rotors in the accelerator closing direction. A second biasing unit biases the accelerator pedal or the pedal rotor in the accelerator closing direction.