Abstract: According to the present invention, a quick charging control means is provided with a power semiconductor which comprises a sapphire substrate and a gallium nitride power transistor that is formed on the sapphire substrate; and a heat dissipation means, which dissipates heat generated during the electric power conversion in the quick charging control means, is bonded to the element outer surface of the gallium nitride power transistor. In one embodiment of the present invention, the power semiconductor employs polarization super junction. In another embodiment of the present invention, the heat dissipation means is connected to at least one of a source region and a drain region in the element outer surface of the gallium nitride power transistor, and extends in the direction away from the sapphire substrate.