Conveying surface 37 has a planar shape. In the carrying surface 37 and the driving surface 30 on the opposite side, in the center portion in the width direction of the timing belt, and has a flat face 31 extending along the length of the timing belt. Along the longitudinal direction on both outer sides of the central portion at predetermined intervals to form the belt teeth (32). All of the driving surface 30 is covered by a canvas (36). Canvas (36) has an elasticity relative to both the longitudinal direction and the width direction of the timing belt.