The present invention relates to a skateboard, which is popular as a short-distance transportation means or for leisure sport, and more particularly, to an electric skateboard using a combination of a generator and motor and a power device for a bicycle. One of said combination of a generator and motor, which has driving wheels, is mounted on either side of a board body, and unpowered auxiliary wheels are mounted on a lower surface of the board body. A control box and a battery for supplying power to or receiving power for the combinations of a generator and motor are coupled to a waist belt. A controller for controlling the combinations of a generator and motor is connected to the control box such that the controller can be held by the hands of a rider. Thus, the skateboard automatically travels and self-charges by means of the combinations of a generator and motor providing a motor function and a generator function, thereby generating and storing power and producing a propulsive force for the skateboard. The skateboard of the present invention is very efficient as it can be applied to both an existing manual skateboard and to an automatic skateboard using electromotive force, and utilized as short- or mid-distance transportation means using electromotive force.