PURPOSE: To reduce the size of an electronic apparatus body using a storage- battery device so as to provide the electronic apparatus body at low costs by a method wherein a clocking operation is started when discharge power to be supplied to the outside from a storage battery is at a prescribed value or lower, a power-off signal is outputted when a prescribed time elapses and the supply of power to the outside from the storage battery is cut off.

CONSTITUTION: Discharge power which is supplied from a storage battery 1 to an external electronic apparatus via terminals 5, 6 is monitored by a discharge-power monitoring circuit 2. That is to say, the discharge-power monitoring circuit 2 monitors the discharge power so as to discriminate the operating state of the external electronic apparatus. Then, when the discharge power is at a predetermined value or lower, the discharge-power monitoring circuit 2 outputs an output signal to that effect. When the output signal is outputted, a timer circuit 3 starts a clocking operation, and it outputs a power- off signal when a prescribed time elapses. When the power-off signal is outputted, a current on/off circuit 4 cuts off the supply of the power of the storage battery 1 to the outside.