In this report, the response characteristics of a hydraulic servomechanism controlled by a throttle valve to the step function response are investigated for the improvement of the electrohydraulic servomechanism for position control. The investigated characteristics are the settling time, which represents the damping and the quick response characteristics of the mechanism, and the initiation boundary of the unstable vibration. The response characteristics are influenced by many system dimensions. Above all, the equivalent damping abilities of the throttle valve and the positioning piston have the most serious effect. It is clarified that the damping abilities are first adjusted to the optimum values corresponding to the input signal and applied load in the design of the servomechanism. Other parameters are subsequently determined to obtain the superior response characteristics.