Motor controller

A motor controller that performs speed sensorless control for a motor, comprising:

• a rotation speed estimating unit that estimates a rotation speed of the motor on the basis of 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 outputs an OFF signal when a portion of the rotating body of the motor is not in proximity;
• a rotation speed computing unit that computes a rotation speed of the motor on the basis of the ON signal and the OFF signal output from the proximity switch;
• and
• an abnormality detection unit that detects an abnormality is a rotation speed estimation value or as abnormality in the proximity switch when a difference between the rotation speed estimation value estimated by the rotation speed estimating unit and a rotation speed computation value computed by the rotation speed computing unit is equal to or larger than a threshold.