PROBLEM TO BE SOLVED: To provide a suction catheter and a suction catheter assembly, capable of removing residual foreign matter even when the foreign matter remains in a lumen of the suction catheter or in a lumen of a guide catheter, in sucking the foreign matter in a blood vessel.SOLUTION: In a suction catheter 2, even when foreign matter remains in a first lumen 11, the first lumen 11 is closed by blocking means 40, whereby the first lumen 11 of the suction catheter 2 can be expanded without back flow of foreign matter remaining in the first lumen 11 into a blood vessel, and suction force of the suction catheter 2 can be recovered. In a suction catheter assembly 1, even when foreign matter remains in a second lumen 21 of a guide catheter 3, the second lumen 21 of the guide catheter 3 is closed by the blocking means 40, whereby the second lumen 21 of the guide catheter 3 can be expanded without back flow of foreign matter remaining in the second lumen 21 of the guide catheter 3 into the blood vessel.
