To uniformly pressurize a film-like material and a base material without generating bubbles therere between.

In the case of laminating a flexible film-like material and a base material, the film-like material and the base material are superposed, filled in a sealable bag having no air permeability, the bag is placed in an airtight chamber without sealing the bag, the chamber is vacumized, then the bag is sealed, thereafter the airtight chamber is brought to vacuum break to bring the film-like material into close contact with the base material, and subsequently the bag is heated and laminated as needed. After the vacuum is broken for more effective laminating, pressurized air may be introduced. In there is not problem in the apparatus, the vacuum breaking may be conducted with a fluid other than the air.