PROBLEM TO BE SOLVED: To provide a catheter assembly which is high in flexibility and has an end part having x-ray contrast properties as well.SOLUTION: A catheter assembly 1 has an external catheter 2 having a long tubular outer shaft 3 and an internal catheter 5 having an inner shaft 6 that can be inserted into an internal cavity of the outer shaft 3. The external catheter 2 has an outer shaft radiopaque part 25 having X-ray contrast properties at an end part of the outer shaft 3. The inner shaft 6 of the internal catheter 5 has an inner shaft radiopaque part 41 having the X-ray contrast properties. The inner shaft radiopaque part 41 exists in an area overlapping the outer shaft radiopaque part 25 in at least a length direction in the state that the inner shaft 6 is inserted into the inner cavity of the outer shaft 3.SELECTED DRAWING: Figure 6【課題】柔軟性が高く、かつ、X線造影性も有する先端部を有するカテーテル組立体を提供する。【解決手段】長尺管状の外シャフト3を有する外カテーテル2と、外シャフト3の内腔に挿通可能な内シャフト6を有する内カテーテル5と、を有し、外カテーテル2は、外シャフト3の先端部にX線造影性を有する外シャフト造影部25を有し、内カテーテル5の内シャフト6は、X線造影性を有する内シャフト造影部41を有し、内シャフト造影部41は、内シャフト6を外シャフト3の内腔に挿通させた状態で、少なくとも長さ方向において外シャフト造影部25と重なる領域に存在するカテーテル組立体1である。【選択図】図6