An electricity recharging device includes a motor provided with an elongated shaft, a coil unit mounted on the motor, a rotary disk secured on the elongated shaft of the motor, a rectifier connected with the coil unit, and a storage battery connected with the rectifier. The coil unit includes at least one coil pole. The rotary disk encompasses the coil unit and has an interior provided with at least one magnet. Thus, when the motor is operated, the elongated shaft drives and rotates the rotary disk relative to the coil unit to produce a magnetic force and to generate an electric current that flows into the storage battery to prolong the usage time of the storage battery.