A method and apparatus to control power supplied to a paper transfer belt (PTB) unit and a laser scanning unit (LSU) included in an image forming device includes the PTB unit to transfer a developed latent image onto a printing medium, the LSU to scan light onto a photosensitive medium, a first controller to control power supplied to the PTB unit and the LSU, and a connection unit to connect the PTB unit to the first controller, wherein the first controller controls the power supplied to the LSU according to a connection state of the connection unit.