To perform energy conservation by operating an induction motor with high efficiency.

This controller 10 for an induction motor comprises an input means 101 for inputting data of an output voltage or an output current I and an output frequency ω from an inverter 14 which operated at a variable speed under a voltage or current control of the induction motor 12 and inputting data of a state α from a sensor 18 for detecting the state α of a load 16 of the motor 12, a calculating means 102 for calculating a voltage command value V' or a current command value I' by using a predetermined calculating formula, based on the data input by the means 101 and torque-speed characteristics of the load 16, and an output means 103 for outputting the value V' or the value I' calculated by the means 102 to the inverter 14.