To detachably connect a leader to a trunk line in a fishing rod rig.

The leader fastener is constituted by integrating a terminal element 2a of a tubular body 2 having a slit 1 with a wedge 4 connecting to a string 3, or using a single wedge 4, and further is provid with a projection 6 adjoining the slit 1. Alternatively, the leader fastener is constituted by integrating a terminal element 22a of the tubular body 22 having a neck part with the slit 11 and a thin shaft 22b, with the wedge 4 connecting to the string 3 or using the single wedge 4, and, is provided with the projection 6 adjoining the slit 1 of the tubular body 2, which is turnable on the thin shaft 22b. Also, the leader fastener is constituted by forming an elongated arm body 66 having two sides or one side and positioned at the projection 6 provided at the tubular body 2 having the slit 1.