A white-level correcting unit makes an image reading unit read a white reference board, and sets a parameter corresponding to a value read by the image reading unit. A carriage includes a light source that irradiates the document, and moves in a sub-scanning direction with respect to a document to be read. When shifting to an energy-saving mode, the image reading device moves the carriage to a position of the white reference board before entering to the energy-saving mode.