An object of this invention is to suppress a decrease in reading efficiency while preventing image degradation. To achieve this object, an image reading apparatus includes a light source which illuminates an object, a sensor which photoelectrically converts light reflected by the object and reads information on the object, a first density reference member which serves as a reference for correcting an image signal obtained by reading an original by the sensor, a second density reference member which is different from the first density reference member, a comparison unit which compares the second signal obtained by reading the second density reference member by the sensor and the third signal obtained by reading again the second density reference member by the sensor, and a correction unit which corrects the image signal on the basis of the first signal obtained by reading the first density reference member by the sensor, and the comparison result of the comparison device.