To provide a surgical instrument which can be used in laparoscopy, which gives little damage to soft tissue, and which can stably operate a soft tissue.SOLUTION: A surgical instrument 10 comprises: a cantilever first beam formed of a material with shaft rigidity to a longitudinal direction being larger than flexural rigidity； a cantilever second beam which is overlaid on the first beam and is formed of a material with shaft rigidity to a longitudinal direction being larger than flexural rigidity； a film connected to a suction pipe and covering the first and second beams； and one or more suction parts provided on the first beam. The suction pipe is connected to a first pump which sucks liquid or gas, and the suction pipe is given a negative pressure by the first pump. The hardness of the first beam and second beam covered with the film is adjusted with a magnitude of the negative pressure.SELECTED DRAWING: Figure 1【課題】腹腔鏡下で用いることができ、軟組織を傷付けづらく、軟組織を安定的に操作することを支援できる手術器具を提供する。【解決手段】手術器具１０は、長手方向に対する軸剛性が曲げ剛性よりも大きいな材質で形成された片持ちの第１梁と、第１梁に重ねて設けられ、長手方向に対する軸剛性が曲げ剛性よりも大きいな材質で形成された片持ちの第２梁と、吸引管に接続され、第１梁及び第２梁を覆うフィルムと、第１梁に設けられた１又は複数の吸引部と、を備え、吸引管は、液体又は気体を吸う第１ポンプに接続され、第１ポンプにより陰圧が加えられ、フィルムにより覆われた第１梁及び第２梁は、陰圧の大きさによって硬さが調整される。【選択図】図１
