A battery pack has a case for storing a battery can, and a metal plane made of a conductive material and connected to the battery can in high frequency is provided on the outer circumference plane of the case. A mounting recessed part for removably mounting the battery pack is provided, and a printed circuit board is provided inside. In the mounting recessed part, a plurality of grounding terminals are electrically connected to a grounding layer of the printed circuit board, on an inner plane to which the metal plane of the battery pack abuts. When the battery pack is mounted in the mounting recessed part, electricity is carried between the metal plane and the grounding terminals, and the metal plane and the battery can are grounded to the grounding layer of the printed circuit board in high frequency.