PROBLEM TO BE SOLVED: To provide a medical instrument capable of molding a sheet-like member in a simplified manner.SOLUTION: A medical instrument 100 for inserting a sheet-like member S into a body, comprises: a cylindrical member 1 an operating rod 2 inserted into the cylindrical member movably in an axial direction and rotatably around the axis, the operating rod 2 having a holding part 21 for holding the sheet-like member S at the tip side along an axial direction of the operating rod and a winding member 3 for taking up the sheet-like member S. On the winding member 3 is formed a hole 31 at least one end of which opens in a surface of the winding member 3 and the inner diameter of which is equal to or less than that of the cylindrical member 1. Also on the winding member 3 is formed a slit which extends in the direction of the axis of the hole 31 from the surface in which the one end of the hole 31 opens, and which communicates with the hole 31.
