PURPOSE: To obtain a deck plate in which dust hardly accumulates around an air nozzle, which has high directional guiding property, and which can be manufactured at a low cost.

CONSTITUTION: Each of air nozzles 36, which are formed on a deck plate 34, is of a triangular shape in its plane form, with its width gradually narrowed as the position moves along the work advancing direction. Moreover, the deck plate corresponding to the base of the triangle is cut, while the inner deck plate portions corresponding to the other two sides of the triangle are folded and projected downward to form a cut-and-pushed-hole. In this case, an inclination angle θ in a side-view between the central part of the upper surface of the downward-projected-part 36a of the air nozzle 36 and the upper surface 34a of the deck plate 34 is formed in a range of 40° to 60°. In addition, in the sectional view perpendicular to the work advancing direction, the upper surface of the downward-projected-part 36a is formed into a circular arc.