A motor controller includes: a rotation speed estimating unit that estimates a rotation speed of a motor based on current information and primary frequency information of the motor; a proximity switch that outputs an ON signal when a portion of a rotating body of the motor is in proximity and that outputs an OFF signal when a portion of the rotating body of the motor is not in proximity; a rotation speed calculating unit that calculates a rotation speed of the motor based on the ON signal and the OFF signal output from the proximity switch; a speed command compensating unit that compensates a speed command value such that an error between the speed command value and a rotation speed calculation value becomes smaller; and a speed control system that perform the speed control on the motor based on the compensated speed command value and the rotation speed estimation value.