PROBLEM TO BE SOLVED: To provide a medical device capable of enhancing the diffusibility of a substance to be administered poured out from a distal end opening while partitioning a plurality of lumens extending in the axial direction. SOLUTION: The medical device is an elongated medical device that punctures a living tissue from a distal end, and has an inner cylindrical portion that defines an inner lumen extending to a tip opening, and a diameter of the inner cylindrical portion. An outer tubular portion that is positioned outward in the direction, defines an outer lumen between the inner tubular portion, and a sidewall has a side wall opening that communicates with the outer lumen； and a tip of the inner tubular portion, The outer tubular portion is located closer to the distal end side than the side wall opening, and the inner tubular portion has a diameter of the inner tubular portion at the distal end side from the side wall opening of the outer tubular portion. A distal end portion is provided that extends toward the side wall of the outer tubular portion located outside in the direction. [Selection diagram] FIG.【課題】軸方向に延在する複数のルーメンを区画しつつ、先端開口から注出される被投与物の拡散性を高めることが可能な医療器具を提供する。【解決手段】医療器具は、遠位端から生体組織に穿刺される長尺状の医療器具であって、 先端開口まで延在する内側ルーメンを区画する内筒部と、前記内筒部の径方向外側に位置し、前記内筒部との間で外側ルーメンを区画し、側壁に前記外側ルーメンに通じる側壁開口が形成されている外筒部と、を備え、前記内筒部の先端は、前記外筒部の前記側壁開口よりも前記遠位端側に位置しており、前記内筒部は、前記外筒部の前記側壁開口よりも前記遠位端側において、前記内筒部の径方向外側に位置する前記外筒部の前記側壁に向かって近づくように延在する先端部を備える。【選択図】図４
