To blow out fins and stains without leaving stuck materials on a processed article without requiring a special closed space.

The fins, burrs, stains or the like of the processed article are blown out with a jet of liquid drops on the surface of the processed article by blowing large numbers of liquid drops together with nitrogen gas from a blow opening 6a of an acceleration route 6. Since the liquid drops and the nitrogen gas around the tip of a jet nozzle 2 are sucked into a sucking opening 3a of a sucking pipe 3, the blown-out fins, burrs, stains or the like are sucked into the sucking opening 3a together with the liquid drops and the nitrogen and the stiuck materials are not left on the processed article.