To provide a high load transmission belt and its manufacturing method capable of efficiently manufacturing the high load transmission belt, firmly fixing blocks and a center belt, and elongating its service life by preventing the abrasion of the blocks and the center belt, the breakage of the center belt, or the like.

In this high load transmission belt 1 provided with the center belt 3 and the plurality of blocks 2 mounted along the longitudinal direction of the center belt 3, the center belt 3 is formed by spirally burying a core wire 5 in an elastomer 4, and having reinforcement cloth at least on one of its upper and lower faces, one block 2 is composed of a resin, and the resin of the block 2 bites into the texture of the reinforcement cloth 6 to anchor the block 2 and the center belt 3.