A sheet-fed duplex and a sheet-fed duplex multi-color printer which is compact, using an electrophotographic printing system. For a long image to be printed on both faces of a sheet of paper, the printer enables producing printed matter at high efficiency and high precision, and yet when printing front and rear faces of a sheet of paper in succession the printer is able to prevent a printing face of the sheet of paper printed on upstream in its conveyance direction from becoming soiled by toner transferred from a printing face of the sheet of paper printed on downstream in its conveyance direction.