PURPOSE: To provide the titled device capable of completely cooling a film with the minimum amount of jet and reducing opacification of the film, by the method wherein an object to be cooled is limited to a horizontal line form part of the outside periphery of a film, and a jet of gas is directed to the line form part substantially perpendicularly.

CONSTITUTION: The film is drawn upwards in a tubular shape while enhancing the viscosity of the resin by an air link 3 provided at the outside periphery of an annular outlet 2a. The entire circumference of the tubular film slightly upstream of a frost line fO is cooled in a line form by a jetting annulus 10 for a secondary cooling gas. Both surfaces constituting an openning part of an annular jetting gap 11 of the jetting annulus are substantially parallel to each other, and the jet collides against the film surface perpendicularly. The film F is cooled from a temperature slightly higher than the solidification start temperature to a temperature slightly lower than the solidification finish temperature while passing through a range in which the jet passed through the gap 11 collides directly against the film F, and a line form recess C capable to be recovered easily is formed.