The balloon catheter of the present invention is provided with a balloon base at a front end of a tubular catheter body having a predetermined length. The balloon base includes a cylindrical base having a larger diameter than an outer diameter of the catheter body, and a lumen having substantially the same diameter as the outer diameter of the catheter body is formed on the base over an entire length with both ends opened. A central axis of the lumen is inclined at a predetermined angle with respect to a central axis of the base concentric with a central axis of the catheter body, and an outer peripheral surface is formed in parallel with the central axis of the base. The balloon is provided on the outer peripheral surface of the parallel base to obliquely inflate with respect to the central axis of the catheter body during inflation.