PURPOSE: To reduce consumption of power source by intermittently lighting a lamp without continuously lighting the same when the lamp is lighted by switching of an external switch.

CONSTITUTION: When an external switch 10 is switched, the signal having been inputted to an AND gate 11 changes from 0 to 1 and only when the signal from a frequency dividing circuit 7 is 1, the AND gate 11 goes ON, along with which a transistor 12 also goes ON. Then, current flows to a lamp 9 to be lighted. When the signal from the frequency dividing circuit 7 is 0, the AND gate is OFF and current does not flow to the lamp 9, thus the lamp is off. Hence, if the signal outputted from the frequency dividing circuit 7 is 1 Hz, it turns out that the lamp 9 repeats lighting of 0.5 second and putting out of 0.5 second. In this way, the consumption of power source by lamp lighting may be made about half.