To position a core bar correctly, to extend the life of a crawler, and to prevent the generation of waves in a steel cable.

A rotary rubber sheet, the core bar 24, and an intermediate rubber sheet are vulcanized to mold an integrated rubber belt 34. Next, the rubber sheet 34 is wound onto the peripheral surface of an inner mold 20. The rubber belt 34, since it is vulcanized, can be positioned easily to the inner mold 20, and the core bar 24 can be set at a prescribed position. Next, the steel cable is wound onto the rubber belt 34. The diameter of the wound cable prevented from being increased by loosening. Next, an unvulcanized grounding surface rubber sheet is wound onto the cable and vulcanized with an outer mold contracted, and a rubber crawler is taken out from the outer mold and the inner mold 20 to produce the seamless, endless crawler.