A medical instrument having a path for receiving a bar-like member and a combination of valves provided in the path. The combination of valves comprises a first disc-like valve having a first slit open only to one of the end faces thereof and a second slit open only to the other of the end faces thereof, the first and second slits crossing each other to form a distance of intersection inside the first valve, and a second disc-like valve disposed in parallel to the first valve and having a slit opening to both end faces thereof. The slit of the second valve crosses the intersection point of the first valve so that the bar-like member passes through the slit of the second valve as well as the intersection of the first valve when it is inserted.