A distal end portion of a tube member is formed to have a smaller outer diameter than a base end portion of the tube member, and a kink is prevented from occurring in a physical property change region where physical properties of a long medical body change relatively largely. A rapid exchange-type medical long body that can be preferably further enhanced by a simple configuration in the vicinity of the base end of the tube member, and a medical instrument set including the medical long body and a catheter are provided. I do. A tube member (150) forming a second region (120B) of a distal member (120) of a medical elongate body (100) is integrally formed with a shaft portion (110), and the distal member moves from a first region (120A) to a second region (120A). A reinforcing layer 160 including a metal material formed between the inner layer 130 and the outer layer 140 over the region, wherein the reinforcing layer is disposed inside the tube member in the second region and is outside the first region. The diameter is formed smaller than the outer diameter of the second region. [Selection diagram] FIG.【課題】チューブ部材の先端部がチューブ部材の基端部よりも外径が小さく形成されるとともに、医療用長尺体において物性が比較的大きく変化する物性変化領域においてキンクが発生するのを防止でき、さらに、チューブ部材の基端部付近における造影性が簡単な構成により好適に高められたラピッドエクスチェンジ型の医療用長尺体、および当該医療用長尺体とカテーテルを備える医療器具セットを提供する。【解決手段】医療用長尺体１００の先端部材１２０の第２領域１２０Ｂを形成するチューブ部材１５０は、シャフト部１１０と一体的に構成されており、先端部材は、第１領域１２０Ａから第２領域に亘って、内層１３０と外層１４０の間に形成される金属材料を含む補強層１６０を有し、補強層は、第２領域においてチューブ部材の内側に配置されており、第１領域の外径は、第２領域の外径よりも小さく形成されている。【選択図】図３
