Abstract: A cooling fan device uses a cooling fan coupled to an engine via a fan clutch to generate cooling air flow for a radiator. The cooling fan device includes an electronic control unit configured to control an engagement rate of the fan clutch. The electronic control unit is configured to execute a first calculation process, a second calculation process, and an upper limit guarding process, thereby controlling the engagement rate based on a value of a coolant temperature requested engagement rate that has been subjected to an upper limit guarding process. A first upper limit rotation speed is set to a lower speed when a vehicle speed is relatively low than when the vehicle speed is relatively high.