PURPOSE: To prevent the parts of material below its folded-back sides from being moved back while it is being carried and realize a proper and efficient folding of the material by a method wherein the parts of the material below its folded-back sides are sprayed with air when the strip-like material is moved reciprocally at a storing part while it is being carried vertically, so that both its sides are folded back to fold the material up.

CONSTITUTION: A strip-like material 3 is carried vertically by a vertical carrying part 4 movable horizontally between both the upper sides of a storing part 1. Both the sides of the material 3 are folded inwardly to fold the material up in the storing part 1. The vertical carrying part 4 is provided with an introducing guide 9 for the material 3, a pull-in roller 10 and a carrying guide 7. A mounting member 6 is fitted over the carrying guide 7 in a freely vertically movable manner. In this case, the mounting member 6 is provided with an air spray device 5 having a pair of left and right air nozzles 5A. When the material 3 is folded back at both the sides of the storing part 1, the air is blown n such a direction as to press the parts of the material below such folded- back sides downwardly or outwardly. This prevents the parts of the material below the folded-back sides from being moved back.