To provide a catheter capable of reliably preventing constriction generated in an entry of a blood vessel collateral when percutaneous coronary intervention is executed against a bifurcated constricyed lesion of the coronary blood vessel.

A catheter includes: a catheter body 210 which inserts a first guidewire to be inserted into a blood vessel root at a collateral part of a coronary blood vessel; a balloon 220 which is provided on the outer peripheral surface of the catheter body 210 and inflates by injection of a pressurizing fluid; cutting blades 230, 240, 250 which project from the outer peripheral surface of the balloon 220 in the diameter direction and follow to the axial direction of the catheter body 210; and a tubular member 260 which is formed on the side of the catheter body 210 and inserts a second guidewire to be inserted into a blood vessel collateral. The cutting blades 230, 240, 250 form a predetermined angle with respect to a straight line connecting the catheter body 210 and the tubular member 260 when viewed at a cross section perpendicular to the axial direction of the catheter body 210.