A medical device to be inserted into a body lumen to obstruct flow in the body lumen includes a shaft unit； a proximal slider and a distal slider that are slidable along the shaft unit； a first expanding member including a distal portion coupled to the proximal slider and a proximal portion coupled to the shaft unit； a second expanding member including a distal portion coupled to the distal slider and a proximal portion coupled to the proximal slider； and a cover that surrounds an outer periphery of the first expanding member and coupled to the proximal portion of the first expanding member, the cover being tubular and flexibly deformable independently of the first expanding member.
