To realize highly accurate machining by eliminating influence on a tool rest provided with a rotating tool exerted by disturbance due to unbalance of the rotating tool in a servo control device for controlling a linear motor for advancing/retreating the tool rest toward a workpiece.

Disturbance exerted on a servo system by rotation unbalance of the rotating tool is predicted from a current command value outputted from a speed feedback loop and a position feedback value outputted from a position detecting device for measuring the position of the tool rest. The predicted disturbance is compensated by a feed forward loop for correcting the current command value inputted into the current feedback loop.