plurality of recessed grooves 82b formed in the second positioning plate 82 when the positioning mechanism 80 is in this engaged state the second positioning plate 82 fastened to the supporting shaft 8 stops the rotation of the take up body 70 via the first positioning plate 81 however when the take up body 70 is caused to pivot by an operating force which exceeds a set force determined by the spring force of the coned disk springs 83 the first positioning plate 81 slides away from the second positioning plate 82 against the force of the coned disk springs 83 so that the engaged state is switched to a disengaged state in which the projecting strips 81c slip out of the recessed grooves 82b formed in the second positioning plate 82 thus allowing rotation of the take up body 70 in other words when an operating force exceeding the set force is applied the positioning mechanism 80 assumes a disengaged state so that the take up body 70 can rotate afterward the positioning mechanism 80 positions the take up body 70 in the prescribed shift position by again switching from a disengaged state to an engaged state the shifting operation of this shifter operating device 5 will be described below with reference to fig3 when the thumb of the hand gripping the handlebar grip is contacts the first finger contact part 22 and the sliding operating body 20 is caused to slide from the home position hp1 in the direction indicated by the arrow i e toward the shift position the first ratchet mechanism 50 transmits the sliding displacement of the sliding operating body 20 as a rotational displacement of the take up body 70 as a result the positioning.