An image reading device including a first carriage including optical elements; a second carriage including optical elements; a carriage driving unit including a pulse motor to move the first and second carriages; a home position sensor to detect a home position of the first carriage; a reference whiteboard to generate shading data and adjust a reference level to be read by the optical elements; a control unit to control the above-described components to read an image of a document through the optical elements; and a counter to count a pulse of a pulse signal driving the pulse motor. The control unit switches directions of movement of the first carriage based on a result output from the home position sensor when the image reading device is returned to an active mode from an energy-saving mode, and detects a distance of movement of the first carriage based on the pulse.