A valve body has: a tubular portion, which is rotatably placed at an inside of a housing; and a partition wall which partitions an inside space of the tubular portion into a first valve chamber located on one axial side of the partition wall and a second valve chamber located on another axial side of the partition wall. A seal member is placed between an inner wall of the housing and the tubular portion of the valve body and extends in a circumferential direction. The seal member partitions an inside space of the housing into a first housing chamber, at which a first fluid inlet and a first fluid outlet of the housing are placed, and a second housing chamber, at which a second fluid inlet and a second fluid outlet of the housing are placed.