Provided is a drag release system of a reel, that system adjusting drag by rotation of a spool on the reel, more particularly, a drag release system that immediately adjusts drag of a spool to prevent cutting of a fishing line by immediately decreasing the drag of the spool when strong tension is applied to the spool during fishing, by forming a fitting hole perpendicular to the axis of a cylindrical driving shaft and forming slits at a sleeve fitted on the driving shaft to have a predetermined length in the longitudinal direction of the driving shaft and to correspond to the fitting hole so that a fixing pin fitted in the fitting hole through the slits prevents the sleeve from idling on the driving shaft and guides the sleeve when the drag is adjusted.
