Abstract: A steering power control device for a power steering system which device is provided with a sensing means which detects the weight of a load carried on a vehicle and a flow control valve which regulates the flow rate of a hydraulic fluid that is supplied to the power steering in response to the detected load, thereby reducing the necessary force to operate the steering wheel when the vehicle load is large. Further, the flow control valve can be regulated also by the output of a vehicle speed sensing means. With the controlling factors of both the vehicle load and the vehicle speed, the operation of the steering wheel is made light when the vehicle speed is low and the vehicle load is large, while the operation of the steering wheel meets with a proper resistance when the vehicle is high and the vehicle load is small, thereby stabilizing the operation of the steering wheel and giving an ideal feeling to a driver in the operation of the steering wheel.