An inverter device includes; a switching element; a plurality of flyback diodes each connected in parallel with the switching element; a first conductor plate connected to anode terminals of the flyback diodes and to one side of the switching element; and a second conductor plate connected to cathode terminals of the flyback diodes and to the other side of the switching element. Each of the flyback diodes is formed in a polygonal shape, and the two flyback diodes in each pair of the flyback diodes that are arranged in mutually adjacent positions are arranged so that a vertex of one opposes a vertex of the other.