An image forming apparatus and a control method thereof are provided. The image forming apparatus includes: an image carrying body which includes a surface on which a developer which corresponds to printing data is applied; a transferring unit which receives transferring electric power to form a transferring area which transfers the developer to a transferring target body; a power supply unit which applies transferring electric power to the transferring unit; and a control unit which controls the power supply unit to apply first transferring electric power or second transferring electric power based on the amount of the developer in a unit section on a surface of the image carrying body. Thus, the present general inventive concept provides an image forming apparatus and a control method thereof for improving a printing image quality.