PROBLEM TO BE SOLVED: To provide a multilumen catheter that can be inserted by a Seldinger retainment technique and can be used for long by preventing obstruction of a subsidiary lumen. SOLUTION: The multilumen catheter has a catheter body 1 having a main lumen 2a, the tip of which is opened, and which is through, a subsidiary lumen 2b, the diameter of which is smaller than the main lumen 2a and the tip of which is closed, and a one-way valve 3 connecting the subsidiary lumen 2b and the outside when the subsidiary lumen 2b is used is provided on the sidewall of the catheter body 1, the one-way valve 3 and the external surface of the periphery thereof are covered with a film made up of a material including at least one kind selected from the group comprising a thrombus generation prevention agent and a thrombus adhesion prevention agent.
