PURPOSE: To simplify a circuit constitution and to accelerate a processing by setting light source light having a white color and the one suitable to the reading of an original and making the light incident on the original so as to read it.

CONSTITUTION: Three color fluorescent lamps 7∼9 are used as a light source incident on an original. In accordance with the drop-out color mode of an arbitrary color or black/white mode, the combination of off/on timing of said fluorescent lamps 7∼9 are changed, and the incident light is caused to be in a black/ white mode or drop-out color mode at the time of CCD1 incident light. Consequently the synthesization of dissolved colors and the discrimination of the picture which is read out strongly and of the color which is not read out and remains white can be carried out by colors of the light source incident on the original.