To provide a medical device that can readily puncture a biological tissue with a puncture member and fix the puncture member inside the biological tissue.SOLUTION: A medical device includes: an elongated puncture member capable of puncture a biological tissue； and a projection member capable of deforming between a projection state of projecting on an outer side in a radial direction more than an outer face of the puncture member and a housing state of not projecting on the outer side in the radial direction more than the outer face of the puncture member.SELECTED DRAWING: Figure 2【課題】容易に穿刺部材を生体組織に穿刺することができ、かつ、穿刺部材を生体組織内に固定することができる医療器具を提供する。【解決手段】医療器具は、生体組織に穿刺可能な長尺状の穿刺部材と、前記穿刺部材の外面よりも径方向外側に突出する突出状態と、前記穿刺部材の外面よりも径方向外側に突出しない収容状態と、の間を変形可能な突出部材と、を備える。【選択図】図２
