Abstract: A welding method heats a surface to be welded of a continuous strip member with a laser beam. The welding method pressurizes the strip member and a continuous film to weld the surface to the film, when or after heating the surface with the laser beam. The welding method preheats the surface before heating the surface with the laser beam. A welding device includes a heat device having an infrared light source disposed to extend along a feed path for the strip member. The heat device is configured to irradiate the surface with infrared light to heat the surface with infrared light. The welding device includes a pressure device configured to pressurize the strip member and the film to weld the surface to the film.