A medical treatment device (12) to treat body tissues for conjugation, includes at least a pair of holding members (52, 54) configured to hold the body tissues, an energy output portion (92, 94) provided in at least one of the holding members and connected to an energy source (14) to form a joined portion by supplying energy to the body tissues held by the pair of holding members and joining the body tissues, and a conjugation coating portion (202) to a region from a neighborhood of a joined portion to coat joined surfaces (C1, C2) with a substance capable of preventing fluid from invading during or after the body tissues being joined by adding the energy to the body tissues.
