A valve device capable of controlling the cooling water of a vehicle's heat-generating element comprises: a housing having a housing body forming an internal space on its inner side, a port connecting the internal space to the outside of the housing body, and a housing opening connecting the internal space to the outside of the housing body; a valve having a valve body rotatable about a rotation axis within the internal space, a valve body internal flow path formed on the inner side of the valve body, a valve body opening connecting the valve body internal flow path to the outside of the valve body, and a shaft provided on the rotation axis, capable of changing the communication state between the valve body internal flow path and the port via the valve body opening according to the rotation position of the valve body; a partition provided at the housing opening to separate the internal space from the outside of the housing body, and capable of supporting the shaft; a drive unit cover provided on the opposite side of the internal space relative to the partition unit, forming a drive unit space between the cover and the partition unit; and a drive unit provided in the drive unit space, capable of rotating and driving the valve body via the shaft.
