A stent delivery system comprises a delivery catheter with a balloon and a stent. The stent delivery system is characterized in that when a force to move the stent in the axial direction of the catheter is applied to the stent, a holding mechanism is formed in a part of the balloon to prevent the stent from falling down. According to this invention, the stent delivery system that is capable of preventing the stent from falling down and has excellent track ability can be provided without requiring complicated manufacturing processes.