PURPOSE: To automatically identify whether an accumulator case is an used one or not when it is loaded on an electronic device.

CONSTITUTION: An accumulator case 1 includes in itself an information storage element 5 controlled by an electronic circuit apparatus 7, a stored information impressing circuit 12 for impressing information stored in the information storage element 5 into the electronic circuit apparatus 7 and a stored information detecting circuit for detecting information stored in the information storage element 5. A stored information erasing circuit for erasing information to be stored, stored in the information storage element is provided in a battery charger and stored information is impressed to a used accumulator case. Thus, an user of the electronic circuit apparatus can identify whether the accumulator case is used one or not when the accumulator case is attached to the electronic circuit apparatus and power is switched on.