An image reading apparatus includes a fingerprint sensor that acquires a plurality of first images obtained by successively reading the portions of a relatively moving object, an extrapolation section that extrapolates the plurality of first images to generate a plurality of second images obtained by extending the image area of the first image, and a relative position detection section that calculates the relative position between the plurality of images or the plurality of second images based on a plurality of images including at least the plurality of first images or the plurality of second images.