An image reading apparatus includes a reading unit, a control unit, and a pattern region. The reading unit moves a linear reading range, which is provided in a main scanning direction, in a sub-scanning direction that intersects with the main scanning direction while reading an object that faces the reading range, and generates image data on the basis of a read result. The control unit controls the reading unit. The pattern region includes a predetermined pattern that defines a reference position for specifying a reading position that is read by the reading unit. The predetermined pattern has a characteristic portion that specifies a schematic position of the predetermined pattern in the sub-scanning direction. The control unit includes a first image acquisition unit, a pattern searching unit, a second image acquisition unit, a characteristic portion searching unit, a first reprocessing instruction unit, and a second reprocessing instruction unit.