PURPOSE: To allow the tip of a projection pressure member to move horizontally while pressed against the surface of a printed wiring board by fitting the projection pressure member to a port member for a projection pressing device for thin film flotation detachably in a slidable state through a spring which presses the projection pressing member against the printed wiring board side all the time.

CONSTITUTION: When the projection pressure member 24 of the projection pressing device for thin film flotation provided on both surface sides operates to peel off a thin film stuck on the printed wiring board, the support member (rotating shaft) 3 of the support member for the projection pressing device moves up and down and is pressed in front of the thin film and a photosensitive film on the surface of the printed wiring board. In this state, the support member (rotating shaft) 3 is rotated to float securely the thin film stuck on the printed board. At this time, the tip of the projectoin pressure member and a support holder 20 for the projection pressure member are pressed by the 1st spring 21 against the printed wiring board side all the time.