There is provided a control valve including a cylindrical casing having an inlet port and a first outlet port for a fluid, and a valve accommodated in the casing to be rotatable around an axis extending in an axial direction of the casing and having a flow path communicating with the inlet port to allow the fluid to flow therethrough, wherein a first communication port communicating with the flow path and the first outlet port according to a rotational position of the valve is formed in the valve, and a fail opening configured to be opened and closed by a thermostat is formed in a portion of the casing facing the inlet port in an opening direction of the inlet port.