An image reading apparatus includes the following. A conveyor conveys a sheet on which an image is formed by an image forming apparatus. An image reader reads the image formed on the sheet. A storage stores a speed variation profile which shows a speed variation for conveying the sheet with the conveyor when the image is read by the image reader. A controller, based on a speed variation profile stored in the storage, controls the conveyor to cancel a variation in speed shown by the speed variation profile, controls the image reader to read a reference mark formed on a sheet by the image forming apparatus, and obtains a forming position of the reference mark.