A medical instrument includes: a rod including a curving portion formed on a distal side of an extension along a longitudinal axis and curved with respect to the longitudinal axis； and a sheath including an inner peripheral surface and a cutout, the cutout formed in at least one of a distal portion and a proximal portion of the sheath, the sheath configured to insert the rod along a central axis extending and defined from the distal portion to the proximal portion and to protrude the curving portion from an opening of the inner peripheral surface in the distal portion.
