[Problem] To provide a catheter that can be placed appropriately by way of facilitating advancing, retracting and placement of the catheter within a curved blood vessel and preventing displacement due to kickback caused during operating a treatment device. [Solution] A high lubrication surface 1 and a low lubrication surface 2 having a greater frictional resistance than the high lubrication surface 1 are disposed at different positions on the circumference of the outer surface of the shaft 3 which are located at the same position in the long axis direction of the shaft 3. The position of the high lubrication surface 1 is indicated by a marker 6 in a proximal part. The high lubrication surface 1 is located on a side in contact with a blood vessel during advancing and retracting to reduce the frictional resistance and facilitate advancing and retracting. When a catheter 10 is placed within the blood vessel, the low lubrication surface 2 is located on the side in contact with the blood vessel to increase the frictional resistance and prevent kickback caused by operating a treatment device 11, thereby facilitating the operation of the catheter 10 and enabling surgery to be finished easily in a short time. Additionally, an introducer or a combination device prevents the catheter from slipping from a hemostasis valve or a piercing part.La présente invention vise à proposer un cathéter qui peut être positionné de manière appropriée en facilitant l'avancement, la rétraction et le positionnement du cathéter à l'intérieur d'un vaisseau sanguin incurvé et en empêchant un déplacement dû à un recul provoqué pendant le fonctionnement d'un dispositif de traitement. À cet effet, selon la présente invention, une surface de lubrification élevée 1 et une surface de lubrification faible 2 ayant une résistance de frottement supérieure à la surface de lubrification élevée 1 sont disposées à différentes positions sur la circonférence de la surface externe de l'arbre 3 qui sont situées à l
