To provide a gas ventilating method for making an appearance of a gas ventilation hole of a weather strip good, and setting the hole making portion and direction freely.

Gas ventilation holes 13a and 13b of a weather strip 1 are formed to even a soft-conditioned molding product 1 immediately after extrusion under a non-contact condition by laser heating, without causing deformation and with a good appearance. By varying a laser radiation focus point, the gas ventilation hole 13b is formed in a manner to penetrate through a dividing wall 9 of plural hollow parts 5a and 7a, and the gas pressure of the hollow parts 5a and 7a is balanced for maintaining a good product shape.