PURPOSE: To provide an industrially used belt of excellent bending fatigue resistance and size stability by a method wherein a reinforcing substance is composed of a cord braided rope in which a core thread is inserted, and the number of twists, the twist direction, and the braiding angle of the cord braided rope and the number of driven threads and the size of the thread core are set to respective proper values.

CONSTITUTION: A reinforcing substance 2 is composed of cord braided rope 7 braided in a cylindrical shape by using the even number of threads being 4-8 to pieces in each of which a cove thread is inserted. A twist factor K of the thread is set to 194±155. The cord braided rope 7 is composed of a dextropotary thread and a leyorotatory thread having a twist direction set in a reverse direction to an S-twist and a Z-twist. A braiding angle is set to 15±5°. When a ratio between the denier number of the thread of the cord braided rope 7 and the denier number of the core thread is set to 3.5-7.5%, when the cord braided rope 7 is braided by four threads, to 7.5-24.0% when it is braided by six threads, and to 14.0-43.0% when it is braided by eight threads.