To prevent the occurrence of an image deflection in a stencil printer in which a printing sheet is separated from a plate cylinder by a separating pawl for injecting air in cooperation with the rotation of the cylinder.

The stencil printer comprises the plate cylinder 1 in which a stencil base sheet is wound and which is rotated, an ink supply means 7 in the cylinder, a pressing roller 11 under the cylinder, the separating pawl 20 for injecting the air from its distal end, an air supply means 25 for supplying the air to the pawl, and a control means 40. The air supply means 25 compresses the air in cooperation with the rotation of the cylinder, and can regulate a discharging pressure under the control of the control means. The control means controls the regulating means of the air supply means with preset table data as a reference in response to the rotating speed of the cylinder, the printing width, margin and printability of the distal end of the printing sheet as factors for affecting the adhering state of the sheet to the cylinder, and sets an injecting pressure from the pawl. Both the soaring of the sheet and the image deflection of the sheet can be suppressed irrespective of the rotating speed of the cylinder and the mage.