[Problem] To reliably mount and hold a stent, with the diameter thereof reduced, on a balloon, said stent being obtained from a biodegradable polymer and being shape-memorized to a size such that the diameter expands to the internal diameter of a blood vessel or greater. [Solution] The invention is obtained from: a stent (2), which is a biodegradable polymer material formed into a tubular shape using polylactic acid having shape memory properties and which is shape-memorized to an expanded diameter size that supports a blood vessel from the inside when implanted inside said blood vessel and a stent-holding member (3) obtained from a biodegradable polymer material, which covers said stent (2) from the outside and holds same with the diameter reduced compared to the shape-memorized size. A stent detection member (8) is installed on the stent (2) and a portion of the stent detection member (8) is fixed to the stent-holding member (3) to prevent the stent (2) from shifting position with respect to the stent-holding member (3).
