Abstract: Disclosed is a hand-operated screw driver with high driving speed/high torque force alternative selection mechanism. A planet gear transmission mechanism is provided having a linking-up shaft and a transmission shaft at two opposite ends respectively alternatively coupled with a driving shaft, which is driven to rotate by a handle, and an output shaft, which drives a screw driver blade for turning screws. The planet gear transmission mechanism is received inside a casing and controlled to rotate by a shift control member to alternatively change the position of the linking-up shaft with the transmission shaft so as to reduce the torque force and increase the speed or reduce the speed and increase the torque force in driving a screw driver blade to turn a screw.