An image reading apparatus capable of performing accurate image correction is provided. The image reading apparatus is provided with a colorimeter which colorimetrically measures an image formed on a sheet based on the optical spectrum in a visible light range, a reference plate located in a position facing the colorimeter with a chromatic reflecting surface, a temperature detection unit configured to detect the temperature of the reference plate, the determination unit configured to determine whether or not the colorimeter is in a normal condition based on the temperature of the reference plate detected by the temperature detection unit and the optical spectrum in the visible light range.