A sheet-fed printer comprising a plurality of sheet-fed duplex printer (2a, 2b, 2c, 2d), wherein the sheet-fed duplex printer (2a, 2b, 2c, 2d) comprises: a pair of impression cylinders (6a, 6b) each provided on a peripheral surface thereof with a paper gripper for gripping a sheet of paper, one of the impression cylinders being in rotational contact with the other impression cylinder disposed downstream in a direction of rotation of and obliquely below the one impression cylinder, the two impression cylinders (6a, 6b) being synchronously rotated so that the regions of rotational contact thereof both move downwards, the sheet of paper reversing its printing face when the sheet of paper conveyed following a peripheral surface of the one impression cylinder is conveyed to follow that of the other impression cylinder; at least a first electrophotographic printing unit disposed opposite to a peripheral surface area of the one impression cylinder which area is upstream in the direction of rotation of the one impression cylinder from the region of rotational contact between the one and the other impression cylinder for printing on one face of the sheet of paper being conveyed following the peripheral surface of the one impression cylinder; and at least a second electrophotographic printing unit disposed opposite to a peripheral surface area of the other impression cylinder which area is downstream in the direction of rotation of the other impression cylinder from the region of rotational contact between the one and the other impression cylinder for printing on the other face of the sheet of paper being conveyed following the peripheral surface of the other impression cylinder; characterised in that said sheet-fed duplex printers (2a, 2b, 2c, 2d) are arranged side by side in a direction of conveyance of the sheet of paper so that the other impression cylinder in said sheet-fed duplex printer at an upstream side is rotationally coupled with the one impression cylinder in said sheet-fed duplex printer at a downstream side; wherein a cleaning unit is disposed opposite to, and adapted to clean, a peripheral surface area of the impression cylinder (6a, 6b) in each of said sheet-fed duplex printers (2a, 2b, 2c, 2d) at a downstream side in the direction of conveyance of the sheet of paper, the peripheral surface of the impression cylinder (6a, 6b) being contacted by a printing face of the sheet of paper printed by each of said sheet-fed duplex printers (2a, 2b, 2c, 2d) at an upstream side in the direction of conveyance of the sheet of paper, the peripheral surface area of the impression cylinder (6a, 6b) being downstream in the direction of its rotation from a position thereon at which the sheet of paper conveyed following the peripheral surface of the impression cylinder (6a, 6b) is transferred therefrom downstream in the direction of conveyance of the sheet of paper; wherein said cleaning unit includes a cleaning roller in rotational contact with said impression cylinder, said cleaning roller and said impression cylinder having a potential difference applicable therebetween for electrophoretically removing toner adhered onto the impression cylinder. a pair of impression cylinders (6a, 6b) each provided on a peripheral surface thereof with a paper gripper for gripping a sheet of paper, one of the impression cylinders being in rotational contact with the other impression cylinder disposed downstream in a direction of rotation of and obliquely below the one impression cylinder, the two impression cylinders (6a, 6b) being synchronously rotated so that the regions of rotational contact thereof both move downwards, the sheet of paper reversing its printing face when the sheet of paper conveyed following a peripheral surface of the one impression cylinder is conveyed to follow that of the other impression cylinder; at least a first electrophotographic printing unit disposed opposite to a peripheral surface area of the one impression cylinder which area is upstream in the direction of rotation of the one impression cylinder from the region of rotational contact between the one and the other impression cylinder for printing on one face of the sheet of paper being conveyed following the peripheral surface of the one impression cylinder; and at least a second electrophotographic printing unit disposed opposite to a peripheral surface area of the other impression cylinder which area is downstream in the direction of rotation of the other impression cylinder from the region of rotational contact between the one and the other impression cylinder for printing on the other face of the sheet of paper being conveyed following the peripheral surface of the other impression cylinder;