A power conversion device comprising: a power conversion unit configured to convert an input power into an output power; and a protective controller configured to stop power conversion by the power conversion unit when at least one value corresponding to the output power of the power conversion unit is not within a target power range determined in accordance with a target value of the output power of the power conversion unit to an electric motor, the target value being calculated from a product of a target torque value and a frequency of the electric motor, wherein the protective controller is configured to use the output power of the power conversion unit as the at least one value corresponding to the output power, and to calculate the output power of the power conversion unit using an output voltage of the power conversion unit, the output voltage being detected by a voltmeter disposed at an output of the power conversion unit, the power conversion unit comprises: a first power converter configured to convert input power into an output power; and a second power converter configured to, using the power output by the first power converter as an input power, convert the input power into an output power, and the protective controller is configured to determine if any one of a first condition, a second condition, or a third condition is established, the first condition being that the output power of the power conversion unit is not within a first target power range, the second condition being that the input power of the power conversion unit is not within a second target power range, the third condition being that the output power of the first power converter or the input power of the second power converter is not within a third target power range, and wherein the protective controller is configured to stop the power conversion by the power conversion unit when any one of the first condition, the second condition, or the third condition is established. a power conversion unit configured to convert an input power into an output power; and a protective controller configured to stop power conversion by the power conversion unit when at least one value corresponding to the output power of the power conversion unit is not within a target power range determined in accordance with a target value of the output power of the power conversion unit to an electric motor, the target value being calculated from a product of a target torque value and a frequency of the electric motor, wherein the protective controller is configured to use the output power of the power conversion unit as the at least one value corresponding to the output power, and to calculate the output power of the power conversion unit using an output voltage of the power conversion unit, the output voltage being detected by a voltmeter disposed at an output of the power conversion unit, the power conversion unit comprises: a first power converter configured to convert input power into an output power; and a second power converter configured to, using the power output by the first power converter as an input power, convert the input power into an output power, and a first power converter configured to convert input power into an output power; and a second power converter configured to, using the power output by the first power converter as an input power, convert the input power into an output power, and the protective controller is configured to determine if any one of a first condition, a second condition, or a third condition is established, the first condition being that the output power of the power conversion unit is not within a first target power range, the second condition being that the input power of the power conversion unit is not within a second target power range, the third condition being that the output power of the first power converter or the input power of the second power converter is not within a third target power range, the first condition being that the output power of the power conversion unit is not within a first target power range, the second condition being that the input power of the power conversion unit is not within a second target power range, the third condition being that the output power of the first power converter or the input power of the second power converter is not within a third target power range, and wherein the protective controller is configured to stop the power conversion by the power conversion unit when any one of the first condition, the second condition, or the third condition is established.