A stent (5), made of a shape-memory alloy and inserted into a stenosed vessel (50), and a stent foundation device for inserting such a stent (5) into a desired part (52) of the stenosed vessel (50) are disclosed. The stent (5) consists of a net-structural hollow cylindrical body (3) made by knitting one longitudinal superelastic shape-memory alloy wire while repeatedly crossing the wire at various points so as to form a plurality of diamond-shape meshes (2). The stent foundation device consists of an actuation steel core (12), a moveable tube (15) and an insert tube (20), which are received within an outside hollow tube (13) while being axially movable within the outside tube. (13). In the above device, an insert tip (23) is connected to the front end of the insert tube (20). The insert tip (23) has a step (22) forming a fitting end, at which the insert tip (23) is partially fitted into the front end of the outside tube (13) and is connected to the front end of the insert tube (20). A thread (21) is fixed at one end thereof to the insert tube (20) at a position spaced apart from the step (22) of the insert tip (23) by a distance. The above thread (21) holds the stent (5) on the insert tube (20) within the outside tube (13).