Stencil printer having ink leakage preventing construction

A stencil printer comprising a printing drum having a perforated construction at a circumferential portion thereof except two annular edge portions extending along opposite axial ends of a cylindrical configuration thereof and a strip of stencil sheet leading end mounting portion extending between said two annular edge portions along a generatrix of the cylindrical configuration, an inking roller provided inside of said printing drum to be shiftable in radially outward and inward directions of said printing drum so as to supply ink to said perforated circumferential portion of said printing drum from the inside thereof while selectively pushing a part of said circumferential portion of said printing drum extending along a generatrix thereof radially outwardly, and a back press roller having a transverse groove formed at a portion of an outer circumferential surface thereof along a generatrix thereof and a clamp for mounting a leading end of a print sheet thereto, said printing drum and said back press roller being arranged in proximity and parallel to one another and adapted to rotate in synchronization with and directions opposite to one another such that said stencil sheet leading end mounting portion is aligned with said transverse groove when they meet one another, thereby executing a stencil printing such that the ink supplied to said perforated portion of said printing drum by said inking roller is selectively transferred through a stencil sheet mounted around said printing drum to provide a printed image of ink on a print sheet supplied between said printing drum and said back press roller with a leading end portion thereof being held by said clamp, wherein the printer further comprises means at least partly carried on said back press roller and adapted to act at said inking roller when said clamp of said back press roller aligns with said inking roller, so as to restrict said radially outward shifting of said inking roller not to press the circumferential portion of said printing drum against said clamp.