1. An electric motor position control apparatus comprising: a position/speed calculation section for calculating speed of an electric motor from a detection position of said electric motor or for calculating a position of said electric motor from a detection speed of said electric motor, a position control section for making said detection position follow a position command value, a speed control section for making said detection speed follow a speed command value depending on the output of said position control section: an electric motor drive section for driving said electric motor on the basis of a torque command value depending on the output of said speed control section, and a control parameter adjustment section having a plurality of sets of control parameters including at least the proportional gain of said position control section and the proportional gain of said speed control section, wherein set selection and the measurement operation of the response state of said electric motor to a position command at the time when said electric motor is controlled by using the control parameters of the selected set are carried out sequentially, and the control parameters of one set are set depending on the result of the measured response.