A flow rate control valve has a housing including a valve body and a main communication hole and auxiliary communication holes. The valve body includes a fluid inflow portion, a main opening portion and auxiliary opening portions formed on the valve body circumferential wall and establish fluid communication. A seal member is provided between the main communication hole and the valve body, and configured to seal between the valve body and the main communication hole. The valve body establishes the communication between one auxiliary communication hole and one auxiliary opening portion regardless of a rotational position of the valve body. In addition, the valve body changes a communication state between the main communication hole and the main opening portion and a communication state between another auxiliary communication hole and another auxiliary opening portion according to the rotational position of the valve body.