PURPOSE: To read a color image and to exactly perform color reproduction by switching a color resolving filter or a reading light source according to the kind of a source document to be read.

CONSTITUTION: Reading light is projected on the rear surface of 3 by using a light source 1 for transmission and a color resolving is performed for transmitted light by a RGB filter 41. At this stage, the filter 41 is composed of total 9 sheets of RGB filter of filters R, G, B to be used when a color film source document is read, filters R', G', B' to be used when a printing source document is read and filters R", G", B" to be used when a photoprint original is read. The transmission characteristic of each RGB filter is made in the following way. Namely, in an optimum filter for color film, a blue peak 440nm, a line peak 555nm and a red peak 660nm are made to be extracted. In an optimum filter for printing source document, 445, 520 and 670nm are made to be extracted in order of blue, green and red. In a filter for photoprint, 450, 520 and 675nm are made to be extracted. After the transmitted light is collected by a image forming lens 5, the light is made to enter a CD sensor 6.