An interconnected inverter system includes an inverter circuit that converts DC power from a DC power supply into AC power and provides AC power to an AC power line, a voltage sensor that detects a voltage of DC power on a DC power supply side of the inverter circuit, a DC current sensor that detects a current of DC power on the DC power supply side of the inverter circuit, and a motor ECU that controls the inverter circuit. The motor ECU calculates actual power of AC power provided from the inverter circuit by using a product of a voltage value detected by the voltage sensor and a current value detected by the DC current sensor and controls the inverter circuit such that calculated actual power follows a power command value from outside of the interconnected inverter system.