To easily obtain a satisfactory image with an original S/N by recommending a user cleaning of a protective glass part, when white correction data exceeds a normal value at the time of white correction.

This device has a manuscript lighting means 101 for lighting the manuscript, a light collecting means 102 for collecting a reflected light from the manuscript, a light detection means 103 for detecting the collected light, a protection material 104 such as glass for protecting the manuscript lighting means 101 and the light collecting means 102, an accumulating means 108 for accumulating white correction data, on the basis of the white correction, a control means 106 that decides that a dirt or dust has stuck to the protective material 104, when the white correction data accumulated in the accumulating means 108 exceeds a normal value and control so as to perform warning, and a warning means 109 for notifying to the effect that dirt or dust has stuck to the protective material 104.