The present invention provides a rubber crawler used for a running unit of a vehicle for farm work, or civil engineering/construction work. Core bars are embedded with a constant spacing in a lengthwise direction of the rubber crawler without steel cords. A closed-loop opening is formed in each of left and right wing portions, which are of a rubber embedding portion of a core bar. The edge portions of the closed-loop openings of the adjacent core bars are fitted into fitting portions with a coupling body including the fitting portions in which both ends are opened in an inward direction. The edge portions are connected with each other at the coupling body to make the coupling body as a counter-tensile material.