PURPOSE: To obtain many bands of good appearance simultaneously, by cutting a belt like object synthetic resin made of moving continuously in its longitudinal direction into a plurality of bands by a slitting device, chamfering edges along its longitudinal direction of the bands moving successively in its longitudinal direction by a chamfering device.

CONSTITUTION: A belt like object 2 made of a synthetic resin is moved in its longitudinal direction, cut into an aimed band width by passing a slitting device (f) and formed into a plurality of the bands 3. Further, these are continuously moved in their longitudinal direction and each band 3 passes a chamfering device (g) and the sharp edges 7 of both sides are chamfered. Then, the band 3 chamfered by said chamfering device (g) passes an annealing apparatus (h) and its structure is made uniform, also residual stress etc. due to stretching is removed. In such a way many bands can be simultaneously manufactured preventing fluffing and longitudinal split.