An inverter device comprising: a substrate provided with a main circuit including a plurality of arm elements, the plurality of arm elements constituting a plurality of upper arm elements and a plurality of lower arm elements, each of the plurality of arm elements including a plurality of semiconductor elements connected in parallel, and each of the plurality of semiconductor elements including a switching element (Q1-Q6) and a flywheel diode (D1-D6) connected in parallel to the switching element; a plurality of input electrode units provided on the substrate and configured to supply power to the main circuit; a plurality of output electrode units provided on the substrate and being connected to a midpoint between the upper and lower arm elements connected in series; and a plurality of input electrodes mounted on the corresponding input electrode units, wherein the plurality of arm elements is arrayed along a first direction of the substrate, each of the arm elements is configured with the plurality of semiconductor elements arrayed along a second direction of the substrate perpendicular to the first direction and the plurality of semiconductor elements is separated into a first element group and a second element group, the substrate includes a first region where the semiconductor element included in the first element group is arranged and a second region where the semiconductor element included in the second element group is arranged, the first region and the second region being separated along the second direction, the input electrode units and the output electrode units are alternately arranged along the first direction, characterised in that the input electrode units and the output electrode units are arranged in a third region provided between the first region and the second region on the substrate, and each of the input electrodes has a rectangular shape of which a width in the first direction is wider than a width in the second direction. a substrate provided with a main circuit including a plurality of arm elements, the plurality of arm elements constituting a plurality of upper arm elements and a plurality of lower arm elements, each of the plurality of arm elements including a plurality of semiconductor elements connected in parallel, and each of the plurality of semiconductor elements including a switching element (Q1-Q6) and a flywheel diode (D1-D6) connected in parallel to the switching element; a plurality of input electrode units provided on the substrate and configured to supply power to the main circuit; a plurality of output electrode units provided on the substrate and being connected to a midpoint between the upper and lower arm elements connected in series; and a plurality of input electrodes mounted on the corresponding input electrode units, wherein the plurality of arm elements is arrayed along a first direction of the substrate, each of the arm elements is configured with the plurality of semiconductor elements arrayed along a second direction of the substrate perpendicular to the first direction and the plurality of semiconductor elements is separated into a first element group and a second element group, the substrate includes a first region where the semiconductor element included in the first element group is arranged and a second region where the semiconductor element included in the second element group is arranged, the first region and the second region being separated along the second direction, the input electrode units and the output electrode units are alternately arranged along the first direction, characterised in that the input electrode units and the output electrode units are arranged in a third region provided between the first region and the second region on the substrate, and each of the input electrodes has a rectangular shape of which a width in the first direction is wider than a width in the second direction.