To provide an inverter device that improves the heat radiation properties of a plurality of power elements that configures a bridge circuit.

In a three-phase AC inverter device of two systems, which drives a motor, power elements on a power supply side in a bridge circuit are mounted on a unit base 71 to configure upper arm units 50 and 60. Power elements on a ground side in the bridge circuit are mounted on a unit base 71 to configure lower arm units 59 and 69. The upper arm units 50 and 60 and the lower arm units 59 and 69 are arranged on upper surfaces 821 and 822 and outer side surfaces 831 and 832 of heat radiation blocks 811 and 812 of a heat sink 80 respectively so as to separate from each other. Thereby, heat generated by the plurality of power elements is radiated to the heat sink 80 as indicated by a broken-line arrow H without interfering with each other.