To suppress noise by controlling without switching loss and additional components.

An electric water pump P starts flow when it is controlled by a pump ECU 7 on the basis of PWM control with a prescribed Duty ratio, and in S2, a radio input state is acquired from a radio 8, and the process advances to S2. In S2, when the radio is ON, the process advances to S3 to acquire the Duty ratio, and the process advances to S4, on the other hand, when the radio is OFF, the process advances to S9 to have the prescribed Duty ratio, then the process is advances to S8 to secure PWM, and the flow is terminated. In S4, when a temperature of cooling water is lower than a target temperature, the process advances to S5 to acquire the target flow rate of cooling water from an engine ECU 5, and the process advances to S6, on the other hand, when the temperature of cooling water is higher than the target temperature, the process advances to S10 to assume 100% Duty, then the process advances to S8 to determine PWM, and the flow is terminated. IN S6, when the flow rate of the cooling water is the target flow rate or more, the process advances to S7 to assume 0% Duty, and the process advances to S8 to determine output PWM, and the flow is terminated, and further when the flow rate of the cooling water is less than the target flow rate, the process advances to S11 to assume 100% Duty, the process is advance to S8 to determine PWM, and the flow is terminated.