A medical device is disclosed for restricting a flow in a body lumen by being inserted into the body lumen. The medical device including an elongated shaft part； an expansion part which is a tubular body having a plurality of gaps and elastically deformable, with the shaft part being connected to at least one of both side end portions of the tubular body； a cover part which is flexibly deformable independently from the expansion part while surrounding an outer circumference of the expansion part, which is tubular in shape, both end portions of the tubular shape being connected to both end portions of the expansion part； and a sheath in which the expansion part and the cover part both contracted in diameter can be accommodated.
