The present invention relates to a catheter, and the catheter (10) is disposed in the outer tube (26) and the outer tube (26), and is guided through the distal end side opening (24b) and the proximal end side opening (24c). And an inner pipe (24) through which (20) is inserted. The outer tube (26) includes at least a first portion (R1) on the distal end side in the axial direction, a second portion (R2) on the proximal end side having higher rigidity than the first portion (R1), and a first portion. A transition part (R0) provided between (R1) and the second part (R2), the rigidity changing from the same rigidity as the first part (R1) to the same rigidity as the second part (R2). Furthermore, the outer pipe (26) is configured by providing an opening (22) in the second portion (R2) to which the proximal end opening (24c) of the inner pipe (24) is connected. .本発明はカテーテルに関し、カテーテル（１０）は、外管（２６）と、外管（２６）内に配置され、先端側開口部（２４ｂ）及び基端側開口部（２４ｃ）を介してガイドワイヤ（２０）が挿通される内管（２４）とを備える。前記外管（２６）は少なくとも、その軸方向で先端側の第１部位（Ｒ１）と、該第１部位（Ｒ１）より剛性が高い基端側の第２部位（Ｒ２）と、第１部位（Ｒ１）と第２部位（Ｒ２）の間に設けられ、第１部位（Ｒ１）と同一の剛性から第２部位（Ｒ２）と同一の剛性へと剛性が変化する移行部位（Ｒ０）とを有し、さらに、前記外管（２６）は、内管（２４）の基端側開口部（２４ｃ）が接続される開口部（２２）を第２部位（Ｒ２）に設けて構成されている。
