In an apparatus for measuring constants of an induction motor (1), an inverter (2) converts an inputted voltage command signal into a single-phase AC power and feeds the single-phase AC power to the induction motor (1) and a current detector (3) detects a current of the single-phase AC power fed to the induction motor (1). An apparatus controller (4) generates a voltage command signal corresponding to an AC voltage to be applied to the induction motor (1) and outputs the voltage command signal to the inverter (2). The apparatus controller (4) generates the voltage command signal and controls the inverter (2) so as to feed the single-phase AC power having a frequency selected in a range equal to or higher than 0.006 Hz and equal to or lower than 1.5 Hz to the induction motor (1). Then a constant calculation controller (5) calculates electric constants of the induction motor (1) based on the voltage and the current of the single-phase AC power fed to the induction motor (1).