a transport unit configured to transport a document in a predetermined transport direction;

a reading unit configured to read the document transported by the transport unit;

a multi-feed detector provided at a position upstream of the reading unit in the transport direction and configured to detect a multi-feed of the document; and

a control unit, wherein

when the multi-feed detector detects the multi-feed of the document, the control unit

acquires a document width from image data generated by the reading unit reading a leading end portion of the document, the document width being a length of the document in a width direction intersecting the transport direction,

determines, based on the document width, whether a size of the document corresponds to a size of a plastic card or an instant film,

does not execute error processing in response to an occurrence of the multi-feed when it is determined that the size of the document corresponds to the size of the plastic card or the instant film, and

executes the error processing when it is determined that the size of the document does not correspond to the size of the plastic card or the instant film.