As shown in FIGS. 5 and 6, thewarp fiber 4a and the woof fiber 4b are so interlaced that the highly adhesive fibers 4a have greater surface area on the side that is stuck to the tooth portion of the toothed belt rubber portion 2, and the fibers 4b, having abrasion-, heat- corrosion-resistance or other properties demanded by the conditions and atmosphere on the engaging side, have greater surface a