To provide a long body for medical treatment, capable of being arranged without being bulky, and improving operability.SOLUTION: A long body 10 for medical treatment includes a long-sized shaft 40 to be inserted into a living body lumen. The shaft 40 has a shaft proximal part 53, a shaft distal part 51, and a shaft intermediate part 52 positioned between the shaft proximal part 53 and the shaft distal part 51. In a state of placing the shaft 40 in a flat reference plane S orthogonal to the gravity direction, the shaft intermediate part 52 curves three-dimensionally and extends while changing a direction to a distal side and a proximal side along a first direction X to which the shaft proximal part 53 extends. A length L1 in a second direction Y of a first portion 52A in contact with the reference plane S of the shaft intermediate part 52, orthogonal to the first direction X and in parallel to the reference plane S is longer than a length L2 in the second direction Y of a second portion 52B at a distal side than the first portion 52A of the shaft intermediate part 52.SELECTED DRAWING: Figure 1【課題】嵩張らずに配置でき、操作性が向上する医療用長尺体を提供する。【解決手段】生体管腔に挿入される長尺状のシャフト４０を有する医療用長尺体１０であって、シャフト４０は、シャフト近位部５３、シャフト遠位部５１、およびシャフト近位部５３とシャフト遠位部５１の間に位置するシャフト中間部５２を有し、シャフト４０を重力方向と直交する平坦な基準面Ｓに載置した状態において、シャフト中間部５２は、シャフト近位部５３が延在する第１の方向Ｘに沿って遠位側および近位側へ方向を替えつつ３次元的に曲がって延在し、シャフト中間部５２の基準面Ｓと接する第１の部位５２Ａの、第１の方向Ｘと直交して基準面Ｓと平行な第２の方向Ｙの長さＬ１は、シャフト中間部５２の第１の部位５２Ａよりも遠位側の第２の部位５２Ｂの第２の方向Ｙの長さＬ２よりも長い。【選択図】図１
