A medical device for body cavity which has a main stent body and a sheet-shaped member having an opening and covering at least a part of the main stent body as described above. It is desirable that, when the main stent body is dilated from the first diameter in the compressed state to the second diameter, the above-described sheet-shaped member spreads so as to cover at least a part of the main stent body without restricting the movement of the main stent body toward the circumferential direction while the shape of the opening of the above-described sheet-shaped member is retained even after the dilation of the main stent body. The above-described medical device for body cavity is applied to a delivery system which has a first catheter for transporting the medical device for body cavity into the body. In this delivery system, the above-described medical device for body cavity is located at the front end of the first catheter as described above so as to allow indwelling thereof.