A drive device for a three-phase rotating electric machine mounted on a vehicle, the drive device comprising: a power supply part; a plurality of switching elements (SW UH ~SW WL) which energize three-phase windings (112U, 112V, 112W) of the three-phase rotating electric machine by performing switching operations for each of three-phase windings; and a control part which controls the switching operations of the plurality of switching elements (SW UH ~SW WL), wherein the control part performs a first control for controlling the switching operations using four energization patterns indicating an ON-state or an OFF-state of the plurality of switching elements (SW UH ~SW WL), thereby driving the three-phase rotating electric machine, in the first control, the control part uses the four energization patterns to control an energization timing of each of a U-phase winding, a V-phase winding and a W-phase winding in the three-phase windings, among the plurality of switching elements, an upper-stage switch and a lower-stage connected in series for energizing the U-phase winding, an upper-stage switch and a lower-stage switch connected in series for energizing the V-phase winding, and an upper-stage switch and a lower-stage switch connected in series for energizing the V-phase winding are connected in parallel between an output side of the power supply part and a ground potential; the drive device being characterized in that in each of the four energization patterns, one of the upper-stage switch and the lower-stage for the U-phase winding and the V-phase winding are configured to be turned on so as to energize the U-phase winding and the V-phase winding, and one of the upper-stage switch and the lower-stage for the W-phase winding is configured to be turn on so as to energize the W-phase winding or both of the upper-stage switch and the lower-stage for the W-phase winding are configured to be turn off so as not to energize the W-phase winding. a power supply part; a plurality of switching elements (SW UH ~SW WL) which energize three-phase windings (112U, 112V, 112W) of the three-phase rotating electric machine by performing switching operations for each of three-phase windings; and a control part which controls the switching operations of the plurality of switching elements (SW UH ~SW WL), wherein the control part performs a first control for controlling the switching operations using four energization patterns indicating an ON-state or an OFF-state of the plurality of switching elements (SW UH ~SW WL), thereby driving the three-phase rotating electric machine, in the first control, the control part uses the four energization patterns to control an energization timing of each of a U-phase winding, a V-phase winding and a W-phase winding in the three-phase windings, among the plurality of switching elements, an upper-stage switch and a lower-stage connected in series for energizing the U-phase winding, an upper-stage switch and a lower-stage switch connected in series for energizing the V-phase winding, and an upper-stage switch and a lower-stage switch connected in series for energizing the V-phase winding are connected in parallel between an output side of the power supply part and a ground potential; the drive device being characterized in that in each of the four energization patterns, one of the upper-stage switch and the lower-stage for the U-phase winding and the V-phase winding are configured to be turned on so as to energize the U-phase winding and the V-phase winding, and one of the upper-stage switch and the lower-stage for the W-phase winding is configured to be turn on so as to energize the W-phase winding or both of the upper-stage switch and the lower-stage for the W-phase winding are configured to be turn off so as not to energize the W-phase winding.