A treatment instrument for joining treating biological tissue (12), the energy holding member and a pair (52, 54), with disposed on at least one of the holding members at least for holding a biological tissue energy output portion forming a joint by joining the living tissues to each other by supplying energy to the living tissue is connected to a source (14), and held by the holding member of the pair and the (92, 94), the living tissue After bonding or during joining by adding energy, and has joint cover portion for covering a material to prevent the penetration of moisture and (202), the bonding surfaces (C1, C2) from near the junction of the living tissue.生体組織を接合処置するための治療用処置具(12)は、生体組織を保持するための少なくとも1対の保持部材(52,54)と、前記保持部材の少なくとも一方に設けられているとともにエネルギ源(14)に接続され、前記1対の保持部材で保持した生体組織にエネルギを供給して生体組織同士を接合して接合部を形成するエネルギ出力部(92,94)と、生体組織にエネルギを付加して接合する際または接合した後に、生体組織の接合部近傍から接合面(C1,C2)を、水分の浸透を防止する物質で覆うための接合被覆部(202)とを有する。
