A method of improving elasticity of a tissue of a living body, the method including: forming a through-hole in the living body； inserting an insertion path forming unit, which includes a pipe member including a pipe and a support member including a support rod, into the through-hole in a state where the pipe member and the support member are assembled； removing the support member from the insertion path forming unit； coupling a medical thread supply unit to the pipe member； pushing the medical thread from behind by using a push unit； and removing the push unit, the medical thread supply unit, and the pipe member.
