Provided is a medical device which can suppress torsion of a wire in a circumferential direction in an expansion body formed using the wire.
Provided is a medical device (10) which enlarges a biological tissue. The medical device (10) includes an elongated shaft portion (20) and an expansion body (21) disposed in a distal portion of the shaft portion (20). The expansion body (21) has a wire portion (50) configured to expand and contract in a radial direction, and a torsion restriction portion (54) that restricts movement of the wire portion (50) in a circumferential direction of the expansion body (21).