An image reading apparatus includes a document feeder, a platen, an image reader, a drive unit, a memory, and a controller. The controller is configured to control the image reader to read a document fed by the document feeder over the platen at a reading position, control the image reader to read a reference plate over the platen at the reading position, to generate read data, determine whether the read data has an abnormality, store a value of the reading position of the image reader in the sub-scanning direction in the memory in response to determining that the read data has an abnormality, set a value of a position of the image reader in the sub-scanning direction to a value being different from the stored value within the predetermined range in response to determining that the read data has an abnormality and in response to receiving a reading instruction of another document, control the drive unit to move the image reader to the position of the set value, and control the image reader to read the other document fed by the document feeder over the platen after the image reader is moved to the position of the set value.