An image reading apparatus includes: a first size-detecting portion which detects a size of an original disposed on a disposing portion; a conveying portion which conveys the original disposed on the disposing portion to a reading portion, a second size-detecting portion which detects the size of the original to be conveyed by the conveying portion; a controller which calculates an overlap region between a reading region and an original region, with the reading region determined based on a reading size obtained by a obtain portion and the detection of the first size-detecting portion, and the original region determined by the second size-detecting portion; and a notifying portion which makes a predetermined notification based on the information that has been calculated.