PURPOSE: To perform parting of a raw fabric web accurately and beside in a state to prevent the occurrence of meandering even when a web surface is locally continued and brought into elongation deformation, in a parting device to part a wide raw fabric web by means of a cutter to form a narrow belt body.

CONSTITUTION: A stretch frame 11 to perform stretching operation of a raw fabric web 1 is arranged in an entrance passage to a cutter 2 for the raw fabric web 1. The stretching frame 11 has a groove 12 brought into external contact with the raw fabric web 1. A vacuum pressure is exerted on the groove 12, a web surface is pulled in the groove 12, and the raw fabric web 1 is forcibly stretched in a longitudinal direction. Under a stretched state, the raw fabric web 1 is parted by means of the cutter 2.