PROBLEM TO BE SOLVED: To rotate a treatment instrument without generation of twisting on an optic fiber.SOLUTION: A trocar 1 for blood recognition comprises: a main body 6 formed of a cylindrical member having opening parts 12a, 12b on both ends, capable of being inserted into a living body, in which an action part 32 of a treatment instrument which is inserted from the opening part 12a on one end side protrudes from the opening part 12b on the other end side； an optic fiber 7 for radiation in which, an injection end 7a is arranged on an end part on the other end side of the main body 6, and radiates a laser beam from the injection end 7a to a biological tissue in the living body； and an optic fiber 8 for light reception in which an incident end 8a is arranged on an end part on the other end side of the main body 6, and receives a scattered light of the laser beam which is scattered by the biological tissue at the incident end 8a.SELECTED DRAWING: Figure 2【課題】光ファイバにねじれを生じることなく処置具を回転させる。【解決手段】両端に開口部１２ａ，１２ｂを有し生体内に挿入可能な筒状の部材からなり、一端側の開口部１２ａから挿入された処置具の作用部３２が他端側の開口部１２ｂから出没可能な本体６と、該本体６の他端側の端部に射出端７ａが配置され、該射出端７ａから生体内の生体組織に向かってレーザ光を射出する照射用光ファイバ７と、本体６の他端側の端部に入射端８ａが配置され、生体組織によって散乱されたレーザ光の散乱光を入射端８ａにおいて受光する受光用光ファイバ８とを備える血管認識用トロッカ１を提供する。【選択図】図２
