Image forming apparatus with roller shifting unit

An image forming apparatus such as a tandem type color image forming apparatus is provided. The image forming apparatus includes a transfer belt (10) that rotates in a rotating direction in which a toner image is transferred. A plurality of color latent image carrying members (20,30,40) are arranged successively along the rotating direction so as to form various color toner images, and a monochrome latent image carrying member (50) is located at any one end of the color latent image carrying members (20,30,40) so as to form a monochrome toner image. A plurality of color transfer rollers (21,31,41) and a monochrome transfer roller (51) are arranged opposite to the color image carrying members and the monochrome latent image carrying member (50) (50), respectively, with the transfer belt (10) therebetween. A roller supporting member (61) supports all of the color transfer rollers (21,31,41). A roller shifting unit (62,63) moves the roller supporting member (61) in a direction in which the color transfer rollers (21,31,41) move toward or away from the color latent image carrying members (20,30,40). The diameters of the color transfer rollers (21,31,41) are smaller than the diameter of the monochrome transfer roller (51). The color transfer rollers (21,31,41) press against the color image carrying members with an appropriate force so that hollow defects are prevented.