PURPOSE: To surely discriminate the kind of a read light source in use and to prevent an original from becoming unreadable in advance.

CONSTITUTION: A read output level obtained from the reflected light of the reference color part 3 of an original covering member 1 emitted from a light source 8 and the reflected light reflected at an identification color part 4 whose wavelength is different from the one of the reference color part 3 is compared with a predetermined threshold value in an in-use light source judgement part, the wavelength of the light source in use is detected and the kind of the light source 8 is judged and outputted.