Abstract: A battery pack housing four tubular cells in juxtaposition to each other in vertical and transverse directions. The battery pack has a cell housing unit, a plurality of cells housed within said cell housing unit, first and second grooves formed on both lateral surfaces of the cell housing unit extending parallel to the direction of insertion of the housing unit into an electronic device, at a mid height along the height of the cell housing unit, and a third groove formed at a mid position along the width of the housing unit extending from the forward end face as far as a mid portion of the housing unit. The first and second grooves are opened in a forward end face of the housing unit in the direction of insertion. The battery device also has a hole formed in a portion of the forward end face of the housing unit not faced by the end faces of the cells housed within the housing unit. An electronic device in which the battery device is loaded has a battery loading section dimensioned to hold the battery device.