An image reading apparatus includes a line sensor to read an image of a document in a read area, a storage unit to store first reference data previously acquired by reading a first white reference member opposite to light receiving elements of the line sensor, a second white reference member of which a length is shorter than a length of the line sensor in the main scanning direction, an acquiring unit to acquire reference data read by the line sensor with the second white reference member and the line sensor opposed to each other, a correction unit to correct an output of the light receiving elements not opposite to the second white reference member, based on the stored first reference data and second reference data acquired by the light receiving elements opposite to the second white reference member among the reference data acquired by the acquiring unit.