An inverter device includes an inverter circuit, which has switching elements in a bridge connection, a capacitor, which is connected in parallel to the input side of the inverter circuit, a control device, which controls the inverter circuit, a temperature detector, which detects the temperature of the capacitor, a degree-of-deterioration determiner, which determines the degree of deterioration of the capacitor, and a warm-up controller. When the temperature of the capacitor detected by the temperature detector is lower than a prescribed temperature, the warm-up controller controls the switching elements of the inverter circuit to supply a direct current set based on the degree of deterioration and the temperature of the capacitor to the coil of an electric motor connected to the output side of the inverter circuit.