To produce a corrugated sheet with stable quality by preventing the corrugated sheet from being crushed and generating inferiority of adhesion caused by no loading.

A pressing apparatus for a double facer in which a pressing body, an expanding body and a pushing body 28 are arranged and an acting body placed above the expanding body and controlling advancing of a fluid medium in the expanding body 22 and movable in the running direction of the corrugated sheet on the expanding body 22 is provided and the acting body is positioned at an arbitrary position in the running direction of the corrugated sheet and a pressing region where a pressing force is applied on the corrugated sheet by means of the pressing body is set and the fluid medium is fed into the expanding body to expand the expanding body and a pressing force is applied on the running corrugated sheet through the pressing body by pushing the pushing body and the pressing body by expanding force of the expanding body, is provided.