To obtain an image reader that can read image information of an original with high accuracy by enhancing read accuracy of a gray scale reference member provided on an original continuous read glass section and correcting a gain of an image signal with high accuracy in the image reader having a continuous read function.

In the image reader that has a 1st image read means reading image information of an original placed or an original mount glass section and a 2nd image read means that reads image information of the original while sequentially feeding originals on an upper part of the original continuous read glass section, a gray scale reference member is placed to an end of the original continuous read glass section with a higher luminance as a result of comparison of the luminance at both ends in light distribution of the original lighting section in the main scanning direction, the image read section reads the gray scale reference member, an output obtained by the image read section is used to correct a temporal change in the luminance of the original lighting section in the main scanning direction and the image information of the original is read.