to the threaded rod 14 then presses the dish member 9 so that the washers 5 6 and friction plates 7 that are brake members are pressed together depending upon the degree of pressing force the power transmission varies between the spool 1 and the shaft 3 if the threaded rod 14 is turned and retracted the power transmission decreases between the spool 1 and the shaft 3 i e the braking members undergo slip in these cases the central folded protrusion 20 of the annular spring 19 is brought into engagement with the tongued and grooved face of the dish member 9 as the drag adjusting knob 12 is turned whereby a holding force is given to the turning operation so that the drag adjusting knob is prevented from loosening according to the present invention as described above the annular spring is inserted in the cylinder with bottom which is secured to the drag adjusting knob a central folded protrusion of the annular spring is protruded beyond a through hole to come into engagement with the tongued and grooved face of the dish member and the drag adjusting knob threaded rod annular spring and spring are assembled together as a unitary structure in the cylinder with bottom therefore the central folded protrusion of the annular spring smoothly and reliably engages with the tongued and grooved face of the dish member maintaining a strong engaging force to impart a suitable holding force to the turn of the drag adjusting knob so that it is prevented from loosening the thus constructed drag mechanism exhibits increased durability and is formed as a unitary structure enabling the.