An image reading apparatus includes a front surface reading sensor configured to read a front surface of a document, a rear surface reading sensor configured to read a rear surface of the document, a storage control unit configured to store image data of the front surface of the document read by the front surface reading sensor and image data of the rear surface of the document read by the rear surface reading sensor, and an encoding unit configured to encode image data of the paired front and rear surface images based on the image data of the front surface and the image data of the rear surface.

An image reading device includes a contact glass, an automatic document feeder, a first reading module, a second reading module, a white reference member, a swinging mechanism, one motor, and a control portion. The swinging mechanism swings the second reading module or white reference member in a direction orthogonal to the conveyance direction. The control portion, by rotating a motor forward, drives a conveying member to convey a document and, by rotating the motor reversely, drives the swinging mechanism with the conveying member at rest to swing the second reading module or white reference member and meanwhile acquire white reference data. When performing a duplex reading process successively for a plurality of sheets of a conveyed document, the control portion acquires the white reference data with the document at rest closely upstream of the second reading module in the conveyance direction.