A stent delivery system includes a housing that houses a rotary roller, a support body in sliding contact with the outer surface of the rotary roller, and a resilient member composed of a coil spring acting on the support body. If, for any reason, it becomes difficult to axially move a rack member and an operator forcibly rotates the rotary roller, a load of not less than a predetermined value is applied to the rotary roller and the rotary roller moves downward while the support body is being pushed down, and meshing engagement between the rack member and the rotary roller is released. Axial movement of the rack member is thus avoided as there is no transmission of the rotating force of the rotary roller to the rack member. Other embodiments are also disclosed for preventing transmission of the rotating force of the rotary roller to the rack member.
