Power generation efficiency is improved with a simple configuration. A braking device is provided with a brake rotor which rotates on a central axis, and friction portions which are in frictional contact with the brake rotor. A coil is wound around the outer peripheral portion of the brake rotor. A friction portion has the north pole of a magnet, and a friction portion has the south pole of a magnet. The braking device generates electricity by using an electromagnetic induction phenomenon and an electrostatic phenomenon that are caused by the interaction between the outer peripheral portion and the friction portion, for example, at the time of braking. As a result, the configuration can be simplified and the amount of power generation is not likely to be limited by a motor capability because there is very little need to use the motor as a generator. Furthermore, the friction energy itself converted from the kinetic energy of the brake rotor can be converted into electrical energy to suppress the friction energy from being lost as heat energy.