An image reading apparatus includes a document feeder; a platen; an image reader configured to read the document, fed by the document feeder, through the platen; a memory; and a controller. The controller causes the image reader to read a reference plate at a predetermined reading position to generate read data, and detecting whether the read data has an abnormality; when the read data has the abnormality, stores a detection position; sets a reading position of the image reader in the sub-scanning direction to a set position spaced by a predetermined range or more from the detection position; when instruction to start reading is received, moves the image reader under standby at a standby position to arrange the image reader at the set position; and reads the document, fed by the document feeder, by the image reader.

An image reading device includes a contact glass, a document transport device, a first reading module, a second reading module, a opposite roller, and roller holders. The opposite roller transports a document while keeping it in close contact with an image reading surface of the second reading module arranged inside the document transport device. The roller holders rotatably support the opposite roller, and on their faces facing the second reading module, a pair of patterns for detection is provided to detect the inclination of the opposite roller. The patterns for detection are each formed to be increasingly wide toward a first end side in the axial direction upstream from an intersection in a central part thereof in the document transport direction, and increasingly wide toward a second end side opposite from the first end side downward from the intersection in the document transport direction.

An image scanner includes a transparent plate, a scanning device, a driving device, a positioning member, a light absorbing portion and a white reference portion. The transparent plate has an original placing surface. The scanning device irradiates an original with light by means of a light source and scans reflected light from the original. The driving device reciprocates the scanning device along the transparent plate. The positioning member positions the original placed on the original placing surface of the transparent plate. The light absorbing portion, which is disposed on the original placing surface side of the positioning member and at substantially a central portion of the positioning member in moving directions of the scanning device, absorbs ambient light entering to the original placing surface side of the positioning member through the transparent plate. The white reference portion is provided to the original placing surface side of the positioning member.