A battery apparatus comprising: a case having a width, a thickness, and a length and including a body section and a bottom section provided in a middle of the body section in a width direction and at one end of the body section in a thickness direction, and having a width which is smaller than the width of the body section, one surface of the body section in a length direction and one surface of the bottom section in the length direction being provided as a same surface, a length of the bottom section in the length direction being smaller than the length of the body section; a battery cell housed inside of the case; a power supply terminal configured to supply an operating current to external electronic equipment from the battery cell; a bottom surface formed at one of surfaces of the bottom section in the thickness direction; and an identification section disposed at a corner located between the same surface and the bottom surface. a case having a width, a thickness, and a length and including a body section and a bottom section provided in a middle of the body section in a width direction and at one end of the body section in a thickness direction, and having a width which is smaller than the width of the body section, one surface of the body section in a length direction and one surface of the bottom section in the length direction being provided as a same surface, a length of the bottom section in the length direction being smaller than the length of the body section; having a width, a thickness, and a length and including a body section and a bottom section provided in a middle of the body section in a width direction and at one end of the body section in a thickness direction, and having a width which is smaller than the width of the body section, one surface of the body section in a length direction and one surface of the bottom section in the length direction being provided as a same surface, a length of the bottom section in the length direction being smaller than the length of the body section; a body section and a bottom section provided in a middle of the body section in a width direction and at one end of the body section in a thickness direction, and having a width which is smaller than the width of the body section, one surface of the body section in a length direction and one surface of the bottom section in the length direction being provided as a same surface, a length of the bottom section in the length direction being smaller than the length of the body section; provided in a middle of the body section in a width direction and at one end of the body section in a thickness direction, and having a width which is smaller than the width of the body section, one surface of the body section in a length direction and one surface of the bottom section in the length direction being provided as a same surface, a length of the bottom section in the length direction being smaller than the length of the body section; a battery cell housed inside of the case; a power supply terminal configured to supply an operating current to external electronic equipment from the battery cell; a bottom surface formed at one of surfaces of the bottom section in the thickness direction; and an identification section disposed at a corner located between the same surface and the bottom surface.