The present invention relates to a medical instrument capable of enhancing the slidability of an operating wire in a lumen. The medical instrument (for example, a catheter (10) of the present invention) includes: a medical instrument body (a sheath (16)) which has a long length and flexibility and is inserted into a body cavity； a lumen (for example, a sub-lumen (30)) which is formed in the medical instrument body along a longitudinal direction of the medical instrument body； and an operating wire (40). The operating wire (40) is accommodated in the lumen, extends along a longitudinal direction of the lumen, and is slidable in the longitudinal direction of the lumen, and the medical instrument body can be bent by an operation of pulling the operating wire (40). A lubricating liquid (45) adheres to at least a surface of the operating wire (40).
