Abstract: The present invention relates to a power source regenerative apparatus which prevents distortion of a voltage regenerating in the power source from being caused. An inverter transforms induction electromotive force caused in regenerating the power source, namely in decelerating the motor, into a direct current. A timing adjusting device outputs a regenerative signal ST at a predetermined timing before the potential of one phase indicative of the maximum potential in three-phase supply voltages becomes the same potential as that of another phase. Based on the regenerative signal ST, a converter converts the transformed direct current into an alternating current, and regenerates it to the power source.