Disclosed herein is an image forming apparatus that has a developing unit, an intermediate transfer body, and a transfer roller and may prevent contamination of the transfer roller and a printing medium by the toner remaining in a test pattern forming area of the intermediate transfer body. The image forming apparatus includes a developing unit to allow an image to be formed by a developing agent, an intermediate transfer body provided with an image forming area and a test pattern forming area, the image being transferred from the developing unit to the image forming area and the test pattern forming area, and a transfer roller allowing the image to be transferred from the image forming area to a printing medium, wherein a maximum transfer length of the transfer roller is less than a maximum image forming length of the developing unit.