An image reading device for reading front and back sides of an original using different reading units has a simple configuration and is capable of matching the input-output characteristic of the front side and the input-output characteristic of the back side and reducing a difference between color on the front side and color on the back side. Based on image data of a color chart read by a front-side reading unit and image data of the color chart read by a back-side reading unit, the image reading device calculates and sets adjustment values for the front and back sides for individual hues of color patches of the color chart and performs adjustment for the front and back sides in accordance with adjustment values corresponding to hue of an original image when the original is read.