An image forming apparatus capable of preventing meandering of a transfer belt. The image forming apparatus includes a main body, including an image forming unit; and a transfer device to transfer an image formed by the image forming unit to a printing medium. The transfer device includes a transfer belt; at least one pair of rollers to rotatably support the transfer belt; a supporting unit to rotatably support both ends of the pair of rollers; and an eccentric unit to movably support a first end of a first roller of the pair of rollers with respect to the supporting unit, the first end deviating from an axis of the first roller.