PURPOSE: To improve a reset effect without increasing the capacity of a capacitor, by providing the 1stW3rd TRs and the capacitor to a reset circuit storing the battery voltage monitoring state of an emergency lamp.

CONSTITUTION: A storing circuit 1 for storing the battery voltage monitoring state is built in a battery failure detecting circuit and a reset circuit 2 is provided to the circuit 1. The reset circuit 2 is provided with a series circuit consisting of a resistor R1 and a capacitor C1 and the 1st TRQ1 for charging the capacitor C1. The 2nd TRQ2 to be turned on by a reset signal from a terminal R is also built in the reset circuit 2 and connected to the TRQ1 in series. The 3rd TRQ3 is turned on by a reset signal from the terminal R to discharge the capacitor C1. During the period from turn-on of the TRQ2 by the reset signal to turn-off of the TRQ1, reset pulses are outputted, so that the reset effect is improved without increasing the capacity of the capacitor C1.