To obtain a plug capable of removing a leader from a head without cutting the leader or removing a connecting part of the leader and readily preparing a device by forming inserting hole of the head so that the connecting part of the leader can be inserted.

This plug is equipped with a head 1 in which an inserting hole 3 for inserting a leader 25 is bored and a skirt attached to the head 1, and the inserting hole 3 is formed so that a connecting part 27 disposed in the leader 25 can be inserted. For example, when the connecting part 27 of the leader is formed in ring-like shape by folding and superposing other end of the leader and pressing the superposed part with a knotting tool 26, the inserting hole 3 is preferably formed of a circular part 3a having diameter larger than vertical cross section shape of the leader 25 and capable of inserting the knotting tool and a protruded part 3b protruded toward the outside direction at a position opposed to the periphery of the circular part 3a and capable of horizontally inserting the connecting part 27 of the leader.