A power conversion apparatus includes a filter circuit, a power conversion circuit, a first casing and a second casing. An input circuit of the filter circuit is connected to a power source to receive power from the power source. A plurality of power conversion circuits are disposed correspondingly to the electrical loads in which every input circuit of the power conversion circuits is connected to an output circuit of the filter circuit and respective output circuits of the power conversion circuits are correspondingly connected to the electrical loads. The power conversion circuit converts the power from the filter circuit and supplies the converted power to the electrical loads. The first casing accommodates the filter circuit and plural second casings are disposed correspondingly to the plurality of power conversion circuits. Each of the second casings accommodates corresponding power conversion circuit.