A stent system includes a catheter having a balloon, and a stent mounted on an outer peripheral portion of the balloon. An outer surface of the balloon and an inner surface of the stent have respective modified surfaces, and adhesiveness between the outer surface and the inner surface is improved by the modified surfaces being in contact with each other. A method for manufacturing the stent system includes applying surface treatment to each of the outer surface of the balloon and the inner surface of the stent to modify the outer surface and the inner surface in such a way as to improve adhesiveness outer surface of the balloon and the inner surface of the stent.