A printing drum of a stencil printing machine is formed of a base member having two annular members spaced apart from each other and a transverse bar connecting the two annular members; a flexible multi-porous sheet having a filled portion at at least a part of a peripheral portion except a central portion thereof and being wrapped into a cylindrical shape around the outer peripheral surface of the base member, and around which a stencil sheet is wrapped; a spring member situated between one end of the flexible sheet and the base member to attach the flexible sheet resiliently on the base member; a stencil clamping device provided on the transverse bar for selectively clamping one end part of the stencil sheet; and an inner pressing device situated inside the flexible sheet for supplying ink outwardly. The inner pressing device pushes the flexible sheet radially outwardly when the base member and flexible sheet assembly rotates. Sliding areas are formed at portions of the annular members contacting the filling portion of the flexible multi-porous sheet. Thus, the flexible sheet can smoothly move on the annular members.