An image reading apparatus includes a gain setting section that sets a gain of a signal from image sensor, a reference data reading section that reads white and black reference data, an image reading section, a correction data generation section that generates correction data by synthesizing a substring extracted from white reference data with a substring extracted from black reference data, and a correction section that performs shading correction of image data using the correction data, wherein in a case where the black reference data is equal to or greater than a predetermined threshold value, the gain setting section performs resetting to lower the set gain, the reference data reading section rereads the black reference data by the reset gain, and the correction data generation section generates correction data by synthesizing the substring of the white reference data with the substring of the black reference data that has been reread.