A movable valve element is provided so as to rotate about a predetermined shaft center. A first valve seat and a second valve seat are respectively arranged apart from the movable valve element with predetermined clearances on both sides of the movable valve element in a direction along the shaft center. A first sealing member is arranged around a communication path so as to seal a space inside the communication path from a space defined by the clearance on a side close to the first valve seat. A second sealing member is arranged around the communication path so as to seal the space inside the communication path from a space defined by the clearance on a side close to the second valve seat.