To provide a control valve capable of suppressing a change in pressure even in case where an inner pressure on a drive part side changes or in case where a pressure on a flow passage side changes, capable of suppressing an influence on operation characteristics of the valve owing to the change in pressure, and capable of effectively preventing a valve function from being impeded when water vapor infiltrates into the drive part side and condensed water freezes after sticking to a plunger serving as a drive mechanism of a valving element.

To a valving element, a diaphragm valving element 58 which is a separation membrane member for air-tightly separating a valve chamber 32 from a drive part 34, is attached. A pressure equalization flow passage 68 which communicates the drive part 34 side with flow passage side, is formed. In the pressure equalization flow passage 68, a dew condensation member 74 is disposed at the flow passage side, and a waterproof moisture permeation member 76 at the drive part 34 side.