In an apparatus for controlling the position of an object driven by a servomotor via a ball screw drive system, parameters of the ball screw drive system are determined from a position command value, an acceleration command value, a torque command value and a motor speed, based on which a dynamic deflection extent while the object is driven at an adjustable speed is calculated. To compensate for this dynamic deflection extent, a deflection compensation command section calculates a deflection compensation value, a deflection speed compensation value, and a deflection torque compensation value. These compensation values are added to their related sections in the position control apparatus individually and collectively compensate for the dynamic deflection.