A balloon catheter capable of expanding a narrowed site of a blood vessel in the vicinity of a curved part of the blood vessel, and of easily adapting the shape of the balloon to the shape of the curved part of the blood vessel. The balloon has a shape with a curved part, and the outer portion of the curved part (the shaded area) formed so as to have a smaller film thickness as compared with the remaining portion of the balloon is stretched by an amount larger than the remaining portion of the balloon. The difference in stretch amount between the outer portion of the curved part of the balloon and the remaining portion of the balloon becomes larger as the internal pressure of the balloon is increased. Accordingly, the extent of curve of the balloon can be controlled arbitrarily by controlling the internal pressure of the balloon. |