A power generation unit includes a motor generator having a rotor with magnet, and a stator with coils driven in a plurality of phases, the coils of the respective phases not being connected to each other; and a driving control part that performs control so that a coil of each phase of the stator is brought into any one of a first state in which torque is generated by the rotor, a second state in which both ends of the coil are electrically released, and a third state in which both ends of the coil are short-circuited.