An electronic device has a flat chassis containing a recording medium mounting unit and a battery mounting unit. In the device, one of the recording medium mounting unit and the battery mounting unit is positioned approximately at the center of the chassis and the other is positioned to one side of the mounting unit positioned approximately at the center of the chassis. An opening of the mounting unit positioned approximately at the center of the chassis is provided on a first end face of the chassis and an opening of the other mounting unit is provided on a second end face of the chassis continuous with the first end face of the chassis.