PURPOSE: To provide an illuminator in which a light guiding body and a circuit board on which a discharge lamp an lighting circuit parts are coupled integrally, a wiring and handling are facilitated, and a particular space is eliminated.

CONSTITUTION: A low voltage discharging lamp 4 is allowed to pass through the insert-through hole 3 formed in a light guiding body 1. light radiated from the discharging lamp 4 is allowed to conduct through the inside of the light guiding body 1 so as to be emitted from one side face of the light guiding body 1, lighting circuit parts 11-14 for lighting the discharge lamp 4 are installed on a circuit board 10 and on the circuit board 10, an engaging part 15 is formed and the detaining part 15 is engaged with the discharge lamp 4 or the light guiding body 1 and the circuit board 10, the low voltage discharge lamp 4 and the light guiding body 1 are coupled integrally.