In a printer in which a printing material is printed on and applied to an object surface via a printing screen mask provided with an opening of a predetermined pattern, cream solder remaining in the opening of the screen mask is removed reliably. A flow rate of the air in an air suction mechanism (19) can be controlled by a flow rate controller (20). After an air sucker (15) has moved up, so that an upper end thereof has contacted the screen mask (5), the sucking of the air is started with respect to the opening (6) of the screen mask (5), whereby a cleaning operation is carried out. The residual cream solder (4) in the opening (6) is examined by an inspection camera (2) after the completion of this cleaning operation, and a cleaning operation is carried out again with the flow rate of the suction air controlled in accordance with the results of the examination.