An inverter control device for driving a motor adapted to utilize a magnet torque generated with a field magnetic flux and an armature current, and a reluctance torque generated with the armature current and an inductance change in an armature winding (51u - 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 including a capacitor having a value adapted to provide an output voltage from the rectification portion pulsing at a frequency 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 for driving the motor corresponding to the smoothened voltage; and an electric-current detection portion adapted to detect the armature current in the motor; wherein the driving control portion includes a magnetic-flux estimation portion adapted to estimate a flux linkage value in the motor based on the armature current detected by the electric-current detection portion, an electric-current phase-difference adjustment portion adapted to adjust a phase difference between the armature current and an induced voltage generated by the motor, and an electric power calculation portion adapted to calculate input electric power to the motor, from the voltage outputted from the DC/AC conversion portion, and from the armature current detected by the electric-current detection portion, and characterised in that the electric-current phase-difference adjustment portion is adapted to perform a phase setting, 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, and an average value of the input electric power to the motor during operation calculated by the electric power calculation portion is equal to a minimum value; wherein the preset flux-linkage value corresponds to a limit value of a total amount Ereg of regenerative energy from the motor charged in the capacitor. a rectification portion to which an AC power supply is inputted; a smoothing portion including a capacitor having a value adapted to provide an output voltage from the rectification portion pulsing at a frequency 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 for driving the motor corresponding to the smoothened voltage; and an electric-current detection portion adapted to detect the armature current in the motor; wherein the driving control portion includes a magnetic-flux estimation portion adapted to estimate a flux linkage value in the motor based on the armature current detected by the electric-current detection portion, an electric-current phase-difference adjustment portion adapted to adjust a phase difference between the armature current and an induced voltage generated by the motor, and an electric power calculation portion adapted to calculate input electric power to the motor, from the voltage outputted from the DC/AC conversion portion, and from the armature current detected by the electric-current detection portion, and characterised in that the electric-current phase-difference adjustment portion is adapted to perform a phase setting, 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, and an average value of the input electric power to the motor during operation calculated by the electric power calculation portion is equal to a minimum value; wherein the preset flux-linkage value corresponds to a limit value of a total amount Ereg of regenerative energy from the motor charged in the capacitor.