The invention concerns the procedure for continuous production of a packing material of the kind which has two plane parallel outer layers (13, 14, 35, 36) containing thermoplastic and where they are kept together by an intermediate layer (1, 28), which has been formed by a plane film containing thermoplastic to a folded form, where the folds are parallel with the production direction of the packing material and where the ridges of the folds are welded together with the out layers. The procedure is primarily characterized by the fact that the intermediate layer is first formed so that its cross-section gets the form of straight sides situated close to each other with an angle between the sides of 50°-90° and with a small rounding of its ridges, that the intermediate layer at the welding is only heated on the outsides of the ridges while the material between the ridges is left cool so that it keeps its strength against deformation and that, at the welding, pressure is applied on the outsides of the outer layers so that at the same time they press the outer layers against each other at which only the material between the ridges of the intermediate layer neutralizes the compression. The invention also concerns a packing material produced according to the procedure.