PURPOSE: To produce torque efficiently by simply obtaining measurement data with respect to one phase of an n-phase reluctance motor and calculating such supply current pattern as maximizing the torque from a torque generation characteristic and a preset loss.

CONSTITUTION: A rotor position detection signal is fed from a rotor position sensor 5a incorporated in a three-phase reluctance motor 5 to an operating section 2, where a read-out address is produced and fed to a pattern table 3. Then the exciting section is split into such number of sections as corresponds to the number of phase. In case of an independent section where only such phase as corresponds to any one section is excited, a supply current pattern for maximizing torque is calculated from a preset loss while in case of a complex section, a supply current pattern for maximizing torque is calculated from a torque generation characteristic derived from measurement data and the preset loss.