An image reading apparatus includes a transparent plate for mounting a sheet, a sheet cover having a light reflecting plate for reflecting light passing through the transparent plate, a storage unit for storing first profile information involving plural darkness data of reflection light from the light reflecting plate detected by an image sensor in advance when a speed of closing the sheet cover is changed variously without the sheet mounted on the transparent plate, and for storing second profile information involving plural darkness data of reflection light detected by the image sensor when the sheet is mounted on the transparent plate and the sheet cover is closed, and a control unit for comparing the first profile information with the second profile information stored in the storage unit, and for determining that a sheet is mounted on the transparent plate when there is a predetermined difference therebetween.