A power converter control method of controlling a direct AC-AC power converter which comprises: a rectifier circuit which inputs first AC voltages (Vr, Vs, Vt) and outputs a rectified voltage (Vdc); and a voltage source inverter which obtains output voltage obtained by modulating the rectified voltage (Vdc) by a modulation factor (k), applies three-phase second AC voltages (Vu, Vv, Vw) to an inductive load, and outputs three-phase load currents (Iu, Iv, Iw) to said inductive load, wherein the modulation factor (k) of said voltage source inverter includes a DC component (k 0) and an AC component (k 6n ·cos(6n·ω L ·t + φ 6n)) which is an angular frequency (6n·ω L) which is a 6n multiple (n is a natural number) of a base fundamental angular frequency (ω L) of said second AC voltage, and when a fundamental wave component, a (6n - 1)th order component and a (6n + 1)th order component of said load current are Iu 1, Iu 6n-1 and Iu 6+1, respectively, and phase differences of said fundamental wave component, said (6n - 1)th order component and said (6n + 1)th order component of said load current from a fundamental wave component of said second AC voltage are φ 1, φ 6n-1 and φ 6n+1, respectively, a ratio (-k 6n /k 0) of an amplitude of said AC component with respect to said DC component takes a ratio represented by − m 6 n 2 + Iu h 6 n 2 + 2 ⋅ m 6 n ⋅ Iu h 6 n cos θ − χ 6 n 1 / 2 / Iu 1 ⋅ cos φ 1 m 6 n = Iu 6 n − 1 2 + Iu 6 n + 1 2 + 2 ⋅ Iu 6 n − 1 ⋅ Iu 6 n + 1 ⋅ cos φ 6 n − 1 − φ 6 n + 1 1 / 2, and a phase difference (φ 6n) of said AC component from the fundamental wave component of said second AC voltage takes an angle represented by tan − 1 m 6 n ⋅ sin χ 6 n + Iu h 6 n ⋅ sin χ 6 n / m 6 n ⋅ cos χ 6 n + Iu h 6 n ⋅ cos χ 6 n ( χ 6 n = tan − 1 Iu 6 n − 1 ⋅ sin φ 6 n − 1 + Iu 6 n + 1 ⋅ sin φ 6 n + 1 / Iu 6 n − 1 ⋅ cos φ 6 n − 1 + Iu 6 n + 1 ⋅ cos φ 6 n + 1, with relationship of Iu h6n < m 6n 1/2 and θ: arbitrary, said method comprising the steps: (a) extracting, from monitored load currents, values of: said fundamental wave component, said (6n-1)th order component, and said (6n+1)th order component of said load current; and the phase differences of said fundamental wave component, said (6n-1)th order component, and said (6n+1)th order component of said load current from said fundamental wave component of said second AC voltage; (b) calculating said ratio (-k 6n /k 0) using the values extracted in said step (a); (c) calculating said phase difference (φ 6n) of said AC component from the fundamental wave component of said second AC voltage using the values extracted in said step (a); and (d) calculating said modulation factor (k), from said ratio (-k 6n /k 0) and said phase difference (φ 6n) calculated in said step (b) and (c), respectively. (a) extracting, from monitored load currents, values of: said fundamental wave component, said (6n-1)th order component, and said (6n+1)th order component of said load current; and the phase differences of said fundamental wave component, said (6n-1)th order component, and said (6n+1)th order component of said load current from said fundamental wave component of said second AC voltage; (b) calculating said ratio (-k 6n /k 0) using the values extracted in said step (a); (c) calculating said phase difference (φ 6n) of said AC component from the fundamental wave component of said second AC voltage using the values extracted in said step (a); and (d) calculating said modulation factor (k), from said ratio (-k 6n /k 0) and said phase difference (φ 6n) calculated in said step (b) and (c), respectively.