An image reading device, which may be incorporated in an image forming apparatus, includes an image reader, a color reference body, a biasing body, a reading gap forming device, and a driving device. The image reader reads an image of an original document. The color reference body has a white reference face to position facing the image reader within a predetermined range in a document width direction. The biasing body biases the color reference body to the image reader. The reading gap forming device forms a reading gap while receiving a biasing force from the biasing body on the outside of the predetermined range. The driving device has a force drive transmission body engaged with a center of the color reference body in the document width direction and drives the color reference body in the document width direction at the center via the force drive transmission body.