PURPOSE: To prevent erroneous insertion even when a light source is not provided with an erroneous insertion preventing structure.

CONSTITUTION: An emission part 1 comprises a plurality of light sources of the same shape and of different emission colors. A light adjustment data for obtaining a required mixture ratio is given to a lighting control part 4 by a process part 3 to provide an emission color selected by a setting part 2. A desired emission color can thus be selected by the emission part 1. The emission color of the emission part 1 is detected by a detection part 5. The emission color of the emission part 1 is judged by the process part 3 based on the detection output of the detection part 5, and it is judged whether the light source is properly installed.