An inverter device comprising: a terminal electrode connected to a circuit substrate having a plurality of semiconductor elements mounted thereon; and a terminal electrode placement member configured to place the terminal electrode therein, and a capacitor substrate having a plurality of capacitors mounted thereon, the capacitor substrate being placed oppositely to the circuit substrate, wherein the terminal electrode includes a substrate-fixed portion secured to the circuit substrate through a fastening member, and an external wiring connection portion to which an external wiring is connected, the substrate-fixed portion and the external wiring connection portion being eccentrically located when viewed from a direction orthogonal to the circuit substrate, the terminal electrode placement member is placed on a surface of the capacitor substrate which is opposite from a surface of the capacitor substrate which is opposite to the circuit substrate and includes a plurality of securing portions which are secured to the circuit substrate, and a rotation suppressing portion configured to suppress a rotation of the terminal electrode, and the rotation suppressing portion is provided with a penetration hole for penetrating the substrate-fixed portion therethrough, and the rotation suppressing portion includes a pair of walls which are opposed to each other and also are positioned in opposite sides beside the terminal electrode which is inserted into the penetration hole at the substrate-fixed portion, the terminal electrode coming into contact with these walls for suppressing the rotation of the terminal electrode. a terminal electrode connected to a circuit substrate having a plurality of semiconductor elements mounted thereon; and a terminal electrode placement member configured to place the terminal electrode therein, and a capacitor substrate having a plurality of capacitors mounted thereon, the capacitor substrate being placed oppositely to the circuit substrate, wherein the terminal electrode includes a substrate-fixed portion secured to the circuit substrate through a fastening member, and an external wiring connection portion to which an external wiring is connected, the substrate-fixed portion and the external wiring connection portion being eccentrically located when viewed from a direction orthogonal to the circuit substrate, the terminal electrode placement member is placed on a surface of the capacitor substrate which is opposite from a surface of the capacitor substrate which is opposite to the circuit substrate and includes a plurality of securing portions which are secured to the circuit substrate, and a rotation suppressing portion configured to suppress a rotation of the terminal electrode, and the rotation suppressing portion is provided with a penetration hole for penetrating the substrate-fixed portion therethrough, and the rotation suppressing portion includes a pair of walls which are opposed to each other and also are positioned in opposite sides beside the terminal electrode which is inserted into the penetration hole at the substrate-fixed portion, the terminal electrode coming into contact with these walls for suppressing the rotation of the terminal electrode.