PROBLEM TO BE SOLVED: To provide a guide tube which enables accurate puncture work while keeping strength in a region inserted into a body cavity.SOLUTION: A guide tube 100 includes a tube body 10 which has a lumen 20 in the inside and is inserted into a body cavity, a puncture opening 30 leading to the lumen 20 and the outside of the tube body 10, and a puncture opening end surface 40 extending in a distal end-proximal end direction of the tube body 10 for sectioning the puncture opening 30. In a transverse section formed by cutting perpendicularly relative to an extending direction of an axial center X of the tube body 10, an opening angle θ formed by two line segments 14 connecting end parts 16 on a side of the axial center X of the puncture opening end surface 40 and the axial center X is less than 180 degrees, and a directional component in an opening direction II included in a normal line I of the puncture opening end surface 40 is configured to be larger than a directional component in the opening direction II of the puncture opening 30 included in a perpendicular line of the line segment 14.SELECTED DRAWING: Figure 3COPYRIGHT: (C)2020,JPO&INPIT【課題】体腔に挿入される領域の強度を維持しつつも正確な穿刺作業を可能とするガイドチューブを提供する。【解決手段】ガイドチューブ１００は、内部にルーメン２０を有し体腔に挿入されるチューブ本体１０と、ルーメン２０とチューブ本体１０の外部とに通じる穿刺開口３０と、チューブ本体１０の先端基端方向に延在し穿刺開口３０を区画する穿刺開口端面４０と、を有し、チューブ本体１０の軸心Ｘの延在方向に対し垂直に切断してなる横断面にて、穿刺開口端面４０の軸心Ｘの側の端部１６と軸心Ｘとを結ぶ二本の線分１４でなす開口角度θが１８０度未満であり、かつ、線分１４の垂線に含まれる穿刺開口３０の開口方向ＩＩの方向成分よりも、穿刺開口端面４０の法線Ｉに含まれる開口方向ＩＩの方向成分が大きくなるよう構成される。【選択図】図３
