Image forming apparatus and belt transporting apparatus with moving member

The image forming apparatus is provided with: an image carrier that holds an image; an endless transfer belt that is rotated while sandwiching a recording medium therebetween, and transfers the image on the image carrier to the recording medium; a first roll member that holds the transfer belt and brings that into contact with the image carrier; a second and third roll members that hold the transfer belt together with the first roll member; and a moving member that makes the second roll member movable so as to make a center distance between the first and second roll members on one end side of the transfer belt larger than one on the other end side, and makes the third roll member movable so as to make a center distance between the first and third roll members on the one end side smaller than one on the other end side.