An inverter control device for driving a motor adapted to utilize a magnet torque generated by a field magnetic flux and an armature electric current, and a reluctance torque generated by the armature electric current and an inductance change in an armature winding (51u, 51v, 51w), in combination with each other, the inverter control device comprising: a rectification portion to which an AC power supply is inputted; a smoothing portion having a capacitor with a value set so that an output voltage from the rectification portion pulses at a frequency which is about twice an AC-power-supply frequency; a DC-AC conversion portion adapted to convert a smoothened voltage from the smoothing portion into a desired AC voltage for driving the motor; a driving control portion adapted to transmit, to the DC-AC conversion portion, information necessary for driving the motor according to the smoothened voltage; and an electric-current detection portion adapted to detect the armature electric current in the motor; wherein the driving control portion includes a magnetic-flux estimation portion adapted to estimate a flux linkage in the motor based on the armature electric current detected by the electric-current detection portion, and an electric-current phase-difference adjustment portion adapted to adjust a phase difference between the armature electric current and an induced voltage generated by the motor, characterized in that the electric-current phase-difference adjustment portion is adapted to perform a phase adjustment, in that an electric-current phase difference (βT) is monotonously increased in steps of a first change width (Δβ1) for performing field weakening operations, such that an estimated flux-linkage value estimated by the magnetic-flux estimation portion is equal to or less than a preset flux-linkage value (λAset, λBset) and then, in that the electric-current phase difference (βT) is changed by a second change width (Δβ2), such that at least one of an average value (Ia* or Tqa*) of an electric-current command value (I*) or a torque command value (Tq*) which is supplied to the motor, an average value (Ia) of an effective value of the armature electric current detected by the electric-current detection portion, and an average value (Ipa) of a peak value of the armature electric current detected by the electric-current detection portion is minimized for controlling a total amount (Ereg) of regenerative energy from the motor to the capacitor. a rectification portion to which an AC power supply is inputted; a smoothing portion having a capacitor with a value set so that an output voltage from the rectification portion pulses at a frequency which is about twice an AC-power-supply frequency; a DC-AC conversion portion adapted to convert a smoothened voltage from the smoothing portion into a desired AC voltage for driving the motor; a driving control portion adapted to transmit, to the DC-AC conversion portion, information necessary for driving the motor according to the smoothened voltage; and an electric-current detection portion adapted to detect the armature electric current in the motor; wherein the driving control portion includes a magnetic-flux estimation portion adapted to estimate a flux linkage in the motor based on the armature electric current detected by the electric-current detection portion, and an electric-current phase-difference adjustment portion adapted to adjust a phase difference between the armature electric current and an induced voltage generated by the motor, characterized in that the electric-current phase-difference adjustment portion is adapted to perform a phase adjustment, in that an electric-current phase difference (βT) is monotonously increased in steps of a first change width (Δβ1) for performing field weakening operations, such that an estimated flux-linkage value estimated by the magnetic-flux estimation portion is equal to or less than a preset flux-linkage value (λAset, λBset) and then, in that the electric-current phase difference (βT) is changed by a second change width (Δβ2), such that at least one of an average value (Ia* or Tqa*) of an electric-current command value (I*) or a torque command value (Tq*) which is supplied to the motor, an average value (Ia) of an effective value of the armature electric current detected by the electric-current detection portion, and an average value (Ipa) of a peak value of the armature electric current detected by the electric-current detection portion is minimized for controlling a total amount (Ereg) of regenerative energy from the motor to the capacitor.