The catheter (10A) is disposed in the catheter hub (30) such that the catheter is sandwiched between the catheter body (20), the catheter hub (30), and the catheter hub (30). And a fixing member (60) having an outer peripheral surface that is in close contact with the inner peripheral surface. Further, the catheter (10A) includes a concave relief portion (55) in which the meat of the catheter body (20) has entered, on a part of the inner peripheral surface of the catheter hub (30) in the circumferential direction.カテーテル（１０Ａ）は、カテーテル本体（２０）と、カテーテルハブ（３０）と、カテーテルハブ（３０）との間にカテーテルを挟持するようにカテーテルハブ（３０）内に配置され、カテーテル本体（２０）の内周面に密着する外周面を有する固定部材（６０）と、を有する。また、カテーテル（１０Ａ）は、カテーテルハブ（３０）の内周面の周方向の一部に、カテーテル本体（２０）の肉が入り込んだ凹状の逃がし部（５５）を備える。
