A position controller includes a position detector, a speed command operator, a first adder, a torque command operator, a second adder, a drive unit, a runout amount correcting device, and a third adder. The runout amount correcting device is configured to employ a value related to deviation between a command value and a detection value in physical quantity of a movable part as a reference signal. The runout amount correcting device is configured to calculate a position correction amount from rotation angle information of the main spindle and the reference signal. The runout amount correcting device is configured to estimate a runout amount of a cutting edge of the tool from the reference signal. The runout amount correcting device is configured to calculate the position correction amount such that influences of the respective cutting edges appearing in the reference signal are leveled.