PURPOSE: To prevent a total amount of light from being remarkably lowered by correcting the amount of controlled light of a light source which is different in the color of emitted light and changing the width of focus conversion for the correction of an amount of light when an amount of controlled light of any light source exceeds the upper limit and the amount of light is largely lowered with the elapse of time and the like.

CONSTITUTION: An amount of light of a light sources 2R to 2B for each color of an illumination device is detected by detectors 2R to 2B for an amount of light and converted into an electric signal, and the ratios R/G, B/R are calculated by dividers 13, 14 by using a G color signal as a reference and compared with a corresponding similar reference ratio in a comparison/calculation parts 9a, 7b, and an amount of light of a light source is controlled in a focus value modifying part 17, a focus judgement part 16, an amount of light data correction part 15, a light controlling devices 4R to 4B and the like to produce a balanced mixture light from appliance 1. At that time, when one of the light sources exceeds the upper limit of controlled light and an amount of light is largely lowered with age and the like, the focus value can be changed in the modifying part 17, and the reduction of an amount of light of the other light sources is controlled, thereby preventing a total amount of light from being remarkably lowered, so that the brightness of original functions may be secured.