Provided is a scanner having sixteen or fewer sensor chips capable of scanning an A4 document; an optical unit that reduces and focuses an image of an A4 document on the sensor chips; and a generator that synthesizes images of the A4 document read by the sensor chips, and generates image data.

Provided is a scanner having: multiple sensor chips; an optical unit that focuses an image of an A4 document on eighteen or more sensor chips; and a generator that synthesizes images of the A4 document read by the sensor chips, and generates image data.