To provide a fixing tool for a catheter with which erosion hardly appear on the nose of a patient.

A catheter fixing part 3 provided with a catheter attaching / detaching member 2 fixes the catheter and is integrally provided on a U-shaped mounting part 1. The catheter fixing part 3 and the U-shaped mounting part 1 are made of silicone rubber or resin incorporating deformable metal, the U-shaped mounting part 1 is made longer on the side making contact with the skin on the outer side of a left nostril 4 than on the side making contact with the skin on the inner side of the left nostril 4, and the catheter is fixed to the nose by mounting the U-shaped mounting part on the left nostril 4. Thus, an adhesive tape to be used can be made smaller than before. Also, when the erosion is to appear, by changing a mounting part to a right nostril 5, the appearance of the erosion is prevented beforehand. Also, since the catheter is fixed without making contact with the skin around the nose by the catheter fixing part 3, the appearance of the erosion on the skin around the nose is prevented.