PROBLEM TO BE SOLVED: To provide a dilator having an excellent guide-wire followability.SOLUTION: A dilator 40 has a lumen 40b which penetrates from a base end side to a tip end side thereof. There are provided: a tube part 40c on the base end side a first outer-diameter decreasing section 44a in which an outer diameter thereof continuously decreases from a tip-end-side end of the tube toward the tip end side and a second outer-diameter decreasing section 44b in which an outer diameter thereof continuously decreases from a tip-end-side end of the first outer-diameter decreasing section to the tip end side. When an axial dimension of the first outer-diameter decreasing section is L1 and an axial dimension of the second outer-diameter decreasing section is L2, L1(d2/L2) is satisfied. The first outer-diameter decreasing section is formed, for example, in an arc shape in which an outline vertical cross section is outwardly convex.SELECTED DRAWING: Figure 3COPYRIGHT: (C)2018,JPO&INPIT【課題】ガイドワイヤ追従性に優れたダイレータを提供すること。【解決手段】基端側から先端側に貫通する内腔40bを有するダイレータ40である。基端側のチューブ部40cと、チューブ部の先端から先端側に向かってその外径が連続的に小さくなる第1外径減少区間部44aと、第1外径減少区間部の先端から先端側に向かってその外径が連続的に小さくなる第2外径減少区間部44bとを有する。第1外径減少区間部の軸方向の寸法をL1、第2外径減少区間部の軸方向の寸法をL2として、L1(d2/L2)である。第1外径減少区間部は、たとえば縦断面の輪郭が外側に凸の円弧状である。【選択図】図3
