To suppress power consumption by a monitoring circuit while reducing the operation load of a user as much as possible.
In a battery pack for an electric apparatus, which includes a secondary battery RB, the monitoring circuit GC to monitor the operating condition of the secondary battery by receiving power supply from the secondary battery RB, and connecting terminals T1, T2 to supply power of the secondary battery to the electric apparatus by making contact with a terminal on the electric apparatus side, a protective cap CC which can freely mounted so as to take a position to cover the connecting terminals T1, T2 is provided, and a current carrying passage to supply power to the monitoring circuit GC from the secondary battery is cut off along with mounting operation of the protective cap CC toward the battery pack side.
OTA KOJI
NISHIYAMA NOBUHISA
