Knife apparatus

A knife apparatus comprising an elongated handle member having longitudinal edge portions bent in opposite to each other so as to form a groove in said handle, at least one of said longitudinal edge portions being formed with a series of teeth, a slide unit disposed longitudinally slidably within said groove of said handle, a blade slidably disposed in said groove in substantially longitudinal alignment with said slide unit and having a base portion connected to said slide unit, a locking member provided in said slide unit and adapted to be movable between a first position at which said locking member meshes with said tooth train to immobilize said slide unit and said blade and a second position at which said slide unit and hence said blade can be moved longitudinally in said groove, a manipulator member disposed on said slide unit over said locking member movably longitudinally relative to said locking member in a predetermined range, and control means provided in combination with said locking member and said manipulator member to selectively move said locking member to one of said first and second positions in response to corresponding operation of said manipulator member, said locking member being formed integrally with said slide unit and having a flexible arm and a lock portion formed at the free end of said flexible arm and adapted to disengageably mesh with said tooth train, said control means including a cam groove provided at the lower side of said manipulator member, and a cam follower stud formed in said lock portion and adapted to be guided by said cam groove.