The present invention relates to a crawler without steel cores (hereinafter referred to as “coreless crawler”), which is used for transporting the caterpillar vehicles for construction, civil engineering, agricultural use or the like. More particularly this invention relates to a coreless crawler for preventing the crawler body from being separated from a wheel or sprocket and the guide roller from riding the guide projection formed on the inward surface of the crawler, by disposing a pair of separation preventing steel cords having an oblique angle, symmetrically with respect to the center portion in the direction of driving so as to balance the deflection forces, thereby extending the lifetime of the crawler product.