A guiding catheter having an outside diameter of 1.4 to 1.6 mm which is to be inserted into a blood vessel and which is capable of being used alone for the purpose of guiding, i.e. being used singly as a guiding catheter and not used together with other guiding catheter or support tube for the purpose of guiding, the catheter comprising: a catheter body which has an inner layer, an outer layer and a reinforcing material layers located therebetween; and a soft tip which is provided on the distal side of the catheter body and more flexible than the catheter body; wherein the catheter body has, at its distal portion, a curved part which has a curved shape and is engageable with a branched portion of the blood vessel due to the curved shape, and the flexural rigidity of the distal-side portion of the catheter body is smaller than the flexural rigidity of the proximal-side portion of the catheter body by 49.03 to 196.13 · 10 -3 N (5 to 20 gf), and the curved part is so configured that the average total thickness of the inner layer, the outer layer and the reinforcing material layer is 60 to 100 μm and the average minimum thickness of the outer layer is 8 to 30 μm, whereby, when the curved part is pushed from the branched portion toward a distal side, the curved part can be deformed according to the shape of a portion on the distal side of the blood vessel, wherein the guiding catheter is designed such that if it is carried alone to the coronary artery orifice of the coronary artery having a stenosis, then a distal portion of the guiding catheter is inserted into the coronary artery orifice, and thereby the guiding catheter is immobilized in that position, prior to insertion of a treatment catheter, wherein the portion on the distal side of the blood vessel is a coronary artery, and the catheter is configured and adapted to be passed through a lumen of a stent having an inside diameter of 2.2 to 3.0 mm which is disposed inside the coronary artery. a catheter body which has an inner layer, an outer layer and a reinforcing material layers located therebetween; and a soft tip which is provided on the distal side of the catheter body and more flexible than the catheter body; wherein the catheter body has, at its distal portion, a curved part which has a curved shape and is engageable with a branched portion of the blood vessel due to the curved shape, and the flexural rigidity of the distal-side portion of the catheter body is smaller than the flexural rigidity of the proximal-side portion of the catheter body by 49.03 to 196.13 · 10 -3 N (5 to 20 gf), and the curved part is so configured that the average total thickness of the inner layer, the outer layer and the reinforcing material layer is 60 to 100 μm and the average minimum thickness of the outer layer is 8 to 30 μm, whereby, when the curved part is pushed from the branched portion toward a distal side, the curved part can be deformed according to the shape of a portion on the distal side of the blood vessel, wherein the guiding catheter is designed such that if it is carried alone to the coronary artery orifice of the coronary artery having a stenosis, then a distal portion of the guiding catheter is inserted into the coronary artery orifice, and thereby the guiding catheter is immobilized in that position, prior to insertion of a treatment catheter, wherein the portion on the distal side of the blood vessel is a coronary artery, and the catheter is configured and adapted to be passed through a lumen of a stent having an inside diameter of 2.2 to 3.0 mm which is disposed inside the coronary artery.