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.