To provide a medical knife which enables the angle of the blade with respect to the grasp portion to be varied with ease without requiring attaching and detaching of the blade and is safe, hygienic and excellent in visibility, the medical knife has a knife body having a grasp portion, a blade and a blade holder portion for holding the blade, a blade cover that covers part of the knife body, and a lock portion that permits the blade cover to be locked in a storage portion for storing the blade in the knife body and in an exposure position for exposing the blade from the knife body, the lock portion permits the blade cover and the knife body to be locked in the storage position and a plurality of exposure positions, and the angles of the blade exposed in the plurality of exposure positions are made mutually different.
