A medical treatment device to treat and join body tissues, includes at least a pair of holding members which is configured to hold the body tissues to be treated, an energy output portion provided in at least one of the pair of holding members and connected to an energy source to form a joined portion by supplying energy to the body tissues held by the pair of holding members to join the body tissues, and a discharge portion which is configured to discharge a substance to cover a surface layer of the joined portion of the body tissues with the substance which prevents infiltration of a fluid into the joined portion after the joined portion is formed.
