A transfer device of an image forming apparatus comprising: a transfer belt to which images formed on a plurality of photoconductors (40Y,40M,40C,40K) are transferred; a plurality of transfer rollers (66Y, 66M, 66C, 66K) corresponding to the plurality of photoconductors (40Y,40M, 40C, 40K), and being movable between transfer positions where the images are transferred to the transfer belt and ready positions separated from the transfer positions; first slider members moving one of the plurality of transfer rollers between the transfer position and the ready position; second slider members moving the remaining transfer rollers (66Y, 66M, 66C) between the transfer positions and the ready positions; and a driving unit moving the first slider members and the second slider members, wherein: the driving unit includes first cam members moving the first slider members and second cam members moving the second slider members; and when the plurality of transfer rollers (66Y, 66M, 66C, 66K) moves from the transfer positions to the ready positions, a time when movement of the first slider members is completed and a time when movement of the second slider members is completed are different characterized in that the first cam members and the second cam members are each connected to a cam rotating shaft passing through both the first slider members and the second slider members; the second slider members extend away from the cam rotating shaft in a first direction; and the first slider members extend away from the cam rotating shaft in a direction opposite to the first direction. a transfer belt to which images formed on a plurality of photoconductors (40Y,40M,40C,40K) are transferred; a plurality of transfer rollers (66Y, 66M, 66C, 66K) corresponding to the plurality of photoconductors (40Y,40M, 40C, 40K), and being movable between transfer positions where the images are transferred to the transfer belt and ready positions separated from the transfer positions; first slider members moving one of the plurality of transfer rollers between the transfer position and the ready position; second slider members moving the remaining transfer rollers (66Y, 66M, 66C) between the transfer positions and the ready positions; and a driving unit moving the first slider members and the second slider members, wherein: the driving unit includes first cam members moving the first slider members and second cam members moving the second slider members; and when the plurality of transfer rollers (66Y, 66M, 66C, 66K) moves from the transfer positions to the ready positions, a time when movement of the first slider members is completed and a time when movement of the second slider members is completed are different characterized in that the first cam members and the second cam members are each connected to a cam rotating shaft passing through both the first slider members and the second slider members; the second slider members extend away from the cam rotating shaft in a first direction; and the first slider members extend away from the cam rotating shaft in a direction opposite to the first direction. the driving unit includes first cam members moving the first slider members and second cam members moving the second slider members; and when the plurality of transfer rollers (66Y, 66M, 66C, 66K) moves from the transfer positions to the ready positions, a time when movement of the first slider members is completed and a time when movement of the second slider members is completed are different characterized in that the first cam members and the second cam members are each connected to a cam rotating shaft passing through both the first slider members and the second slider members; the second slider members extend away from the cam rotating shaft in a first direction; and the first slider members extend away from the cam rotating shaft in a direction opposite to the first direction.