A medical device includes, a vibration transmitting member configured to be capable of transmitting vibration for use in a treatment; a jaw configured to move between an abutted position where the jaw abuts on the vibration transmitting member, and a spaced position where the jaw is spaced apart from the vibration transmitting member; and a cover provided in such a position that the vibration transmitting member is interposed between the cover and the jaw, and configured such that a first distal portion, which is located at a distal end of the cover, comes in contact with the vibration transmitting member, when the jaw is located in the abutted position.