An image reading device includes a feeding unit, a reading unit, and a processor. The feeding unit is configured to feed a plurality of sheets of original document one by one. The reading unit is configured to read an image on each of the plurality of sheets fed by the feeding unit and generate image data representing the image. The processor is configured to function as a selecting unit and a determining unit. The selecting unit is configured to select a criterion from among a plurality of criteria. The determining unit is configured to determine, according to the criterion selected by the selecting unit, whether or not a sheet of the original document is actually fed while being overlapped with another sheet of the original document based on image data corresponding to the sheet.