To provide a dilator which can easily enlarge a diameter of a hole formed on a wall of digestive tract or the like.SOLUTION: A dilator 30 includes a hollow-shaped shaft 31 in which an outer diameter of a distal end is smaller than an outer diameter of a proximal end and a connector 9 provided on the proximal end of the shaft 31. On an outer peripheral surface 31B of the shaft 31, a spiral protruding part 32 protruding to the outside is provided. The spiral protruding parts 32 have a gap in an adjacent part along an axis A of the shaft 31. The shaft 31 has a first position P5 and a second position P6 which is positioned more on the distal end side from the first position P5 and has an outer diameter smaller than an outer diameter in the first position P5 along the axis. As regards a tilting angle of the spiral protruding part 32 relative to the axis A, the tilting angle at the second position P6 is smaller than the tilting angle at the first position P5.SELECTED DRAWING: Figure 4【課題】消化管等の壁に形成された孔を容易に拡径することができるダイレータを提供する。【解決手段】ダイレータ３０は、先端の外径が基端の外径よりも小さい中空形状のシャフト３１と、シャフト３１の基端に設けられたコネクタ９とを備える。シャフト３１の外周面３１Ｂに、外部に突出する螺旋状の凸部３２が設けられている。螺旋状の凸部３２は、シャフト３１の軸Ａに沿って隣り合う部分に隙間を有する。シャフト３１は、軸に沿った、第１位置Ｐ５と、第１位置Ｐ５よりも先端側に位置し外径が第１位置Ｐ５における外径よりも小さい第２位置Ｐ６とを有する。螺旋状の凸部３２の軸Ａに対する傾斜角は、第１位置Ｐ５よりも第２位置Ｐ６の方が小さく構成される。【選択図】図４
