A battery charger includes a battery attachment section configured to have a rechargeable battery releasably attached thereto. The battery attachment section includes a flat attachment surface having a width corresponding to a width of a bottom surface of a case of the battery to be charged and a length greater than a length of the bottom surface of the case of the battery to be charged; a plurality of locking hooks provided on the attachment surface; a charger terminal configured to contact a terminal of the battery to be charged, the charger terminal including a plurality of plate-shaped contact pieces configured to be inserted into engaging grooves of the battery to be charged; and an attachment projection adjacent to the attachment surface and configured to secure the battery to the charger.