An inverter device connected to an AC system via a reactor, the inverter device comprising: a conversion unit (10, 11) configured to convert DC power outputted from a power supply, to AC power, and output the converted AC power to the AC system via the reactor; and a control unit configured to control the conversion unit (10, 11), wherein the conversion unit (10, 11) includes: a step-up circuit configured to step up a DC input voltage value of the DC power; and an inverter circuit configured to convert power given from the step-up circuit, to AC power, wherein: the control unit is adapted to calculate an output current target value based on an input power value of the DC power and a voltage value of the AC system, and calculate a current target value and a voltage target value for the inverter circuit based on the output current target value, to control the inverter circuit, determine, as a voltage target value for the step-up circuit, a greater one of the DC input voltage value and an absolute value of the voltage target value for the inverter circuit, so that when the greater one is the absolute value of the voltage target value, the step-up circuit executes a switching operation whereas the inverter circuit stops a switching operation, and when the greater one is the DC input voltage value, the step-up circuit stops the switching operation whereas the inverter circuit executes the switching operation, and calculate a current target value for the step-up circuit based on a current target value and a voltage target value that are common with the inverter circuit, and on the DC input voltage value, to control the step-up circuit, and thereby control output of the AC power. a conversion unit (10, 11) configured to convert DC power outputted from a power supply, to AC power, and output the converted AC power to the AC system via the reactor; and a control unit configured to control the conversion unit (10, 11), wherein the conversion unit (10, 11) includes: a step-up circuit configured to step up a DC input voltage value of the DC power; and an inverter circuit configured to convert power given from the step-up circuit, to AC power, a step-up circuit configured to step up a DC input voltage value of the DC power; and an inverter circuit configured to convert power given from the step-up circuit, to AC power, wherein: the control unit is adapted to calculate an output current target value based on an input power value of the DC power and a voltage value of the AC system, and calculate a current target value and a voltage target value for the inverter circuit based on the output current target value, to control the inverter circuit, determine, as a voltage target value for the step-up circuit, a greater one of the DC input voltage value and an absolute value of the voltage target value for the inverter circuit, so that when the greater one is the absolute value of the voltage target value, the step-up circuit executes a switching operation whereas the inverter circuit stops a switching operation, and when the greater one is the DC input voltage value, the step-up circuit stops the switching operation whereas the inverter circuit executes the switching operation, and calculate a current target value for the step-up circuit based on a current target value and a voltage target value that are common with the inverter circuit, and on the DC input voltage value, to control the step-up circuit, and thereby control output of the AC power. calculate an output current target value based on an input power value of the DC power and a voltage value of the AC system, and calculate a current target value and a voltage target value for the inverter circuit based on the output current target value, to control the inverter circuit, determine, as a voltage target value for the step-up circuit, a greater one of the DC input voltage value and an absolute value of the voltage target value for the inverter circuit, so that when the greater one is the absolute value of the voltage target value, the step-up circuit executes a switching operation whereas the inverter circuit stops a switching operation, and when the greater one is the DC input voltage value, the step-up circuit stops the switching operation whereas the inverter circuit executes the switching operation, and calculate a current target value for the step-up circuit based on a current target value and a voltage target value that are common with the inverter circuit, and on the DC input voltage value, to control the step-up circuit, and thereby control output of the AC power.