PURPOSE: To hold an optimum printing pressure by providing an actuator using compressed air to vertically move a squeegee, an electropneumatic regulator for varying the pressure of compressed air to be supplied to the actuator by an electric signal, and a solenoid valve for switching the flowing direction of the air.

CONSTITUTION: When compressed air is supplied to the upper end of an actuator 17 through a solenoid valve 21 and an electropneumatic regulator 20, a piston rod 19 is moved down. A squeegee 14 is moved down through a holder 15 and guide shafts 16a, 16b to be brought into contact with a screen 11, and further energized downward. A force for energizing the squeegee 14 downward (printing pressure) is decided by the pressure of the compressed air set by the regulator 20. Even if the height size of a printed board 13 is varied on the way of moving the plate 18, the force for energizing the squeegee 14 down (printing pressure) is not varied, but an optimum printing pressure set by the regulator 20 is held.