Battery device and electronic apparatus

A battery apparatus and an electronic equipment are provided which permit the use of a plurality of types of battery apparatuses that differ in capacity, and are advantageous in improving ease of use. A case of a battery apparatus has a main body portion and a bottom portion disposed at one side in a thickness direction at the midpoint in a width direction of the main body portion. Portions on both sides in the width direction of the case are formed as flat side surfaces that are parallel to each other and extend in a length direction. A plane on one side in the thickness direction of the case is formed as a flat bottom surface. At portions of the case on both sides in the width direction, guide grooves are formed which extend in the length direction and engage projections disposed at a battery housing chamber thereby to position the position of the case in the thickness direction within the battery housing chamber.