of the cylindrical section 44 at this time the sliding bearing 32 is inserted between the outer peripheral surface of the displacement shaft 35 and the inner peripheral surface of the cylindrical section 44 a thrust washer 41 fabricated from an easily sliding material is interposed between one end of the cylindrical section 44 and the base end section 37 of the rocker member 12a another thrust washer 42 is fitted around the tip section of the displacement shaft 35 which projects from the other end opening of the cylindrical section 44 the left end in fig7 and the stopper ring 39 is held in the engaging groove 40 provided in the tip section of the displacement shaft 35 outside the thrust washer 42 as a result the rocker bearing section is formed so that the rocker member 12 is supported in a freely swinging manner with respect to the fixed member 10 in the autotensioner with this structure in this embodiment it is not necessary for the bolt for securing the fixed member 10 to the front surface of the cylinder block to penetrate the rocker bearing section this bolt only penetrates the two round holes 30 30a formed on the lower side section of the fixed member 10 therefore even in the case where the formation of a threaded hole is impossible in the section of the cylinder block corresponding to the rocker bearing section the direction at which the pulley 5 presses against the belt 1 can be the optimum direction or close to the optimum direction also the position at which the two round holes 30 30a are formed is freely changeable to an optional position corresponding to.