To avoid ill effect on other luminaires and electric facilities due to failure even if leakage, short circuit or lamp lighting error occurs during installation in a general switch-on system and maintain a luminaire in failure without generally switching off.

A box 5 is integrally provided on a luminaire mainbody 1 for storing a switch or a breaker 8 so that power can be supplied via the breaker 8 (or the switch) to shut off a luminaire itself, when in failure, from leakage. A power supply passage for the luminaire in failure can also be shut off independently.