A power conversion apparatus configured to be connected with a plurality of DC power-supply devices (1a-1e), comprising: a plurality of connectors (2a-2e) configured to be connected with the DC power-supply devices (1a-1e); a plurality of voltage transducers (3a-3e) connected in series with the plurality of connectors (2a-2e); a plurality of DC power output lines (6A-6C) electrically independent from one another and having different set voltages; and a switching part configured to selectively connecting the plurality of voltage transducers (3a-3e) and the plurality of DC power output lines (6A-6C) with each other, characterized in that the power conversation apparatus further comprising: a controller configured to control the switching part, according to the operating state of at least either the plurality of DC power-supply devices (1a-1e) or loads connected to the plurality of DC power output lines (6A-6C), wherein: the controller is configured to control the switching part so that each of the plurality of voltage transducers (3a-3e) is connected to only one line of any of the plurality of the DC power output lines (6A-6C); and the controller controls the switching part such that a first voltage transducer in the plurality of voltage transducers (3a-3e) which is connected to a DC power-supply device having a relatively high output voltage is connected to a DC power output line having a relatively high set voltage, and a second voltage transducer in the plurality of voltage transducers which is connected to a DC power-supply device having a relatively low output voltage is connected to a DC power output line having a relatively low set voltage. a plurality of connectors (2a-2e) configured to be connected with the DC power-supply devices (1a-1e); a plurality of voltage transducers (3a-3e) connected in series with the plurality of connectors (2a-2e); a plurality of DC power output lines (6A-6C) electrically independent from one another and having different set voltages; and a switching part configured to selectively connecting the plurality of voltage transducers (3a-3e) and the plurality of DC power output lines (6A-6C) with each other, characterized in that the power conversation apparatus further comprising: a controller configured to control the switching part, according to the operating state of at least either the plurality of DC power-supply devices (1a-1e) or loads connected to the plurality of DC power output lines (6A-6C), wherein: the controller is configured to control the switching part so that each of the plurality of voltage transducers (3a-3e) is connected to only one line of any of the plurality of the DC power output lines (6A-6C); and the controller controls the switching part such that a first voltage transducer in the plurality of voltage transducers (3a-3e) which is connected to a DC power-supply device having a relatively high output voltage is connected to a DC power output line having a relatively high set voltage, and a second voltage transducer in the plurality of voltage transducers which is connected to a DC power-supply device having a relatively low output voltage is connected to a DC power output line having a relatively low set voltage. a controller configured to control the switching part, according to the operating state of at least either the plurality of DC power-supply devices (1a-1e) or loads connected to the plurality of DC power output lines (6A-6C), wherein: the controller is configured to control the switching part so that each of the plurality of voltage transducers (3a-3e) is connected to only one line of any of the plurality of the DC power output lines (6A-6C); and the controller controls the switching part such that a first voltage transducer in the plurality of voltage transducers (3a-3e) which is connected to a DC power-supply device having a relatively high output voltage is connected to a DC power output line having a relatively high set voltage, and a second voltage transducer in the plurality of voltage transducers which is connected to a DC power-supply device having a relatively low output voltage is connected to a DC power output line having a relatively low set voltage. the controller is configured to control the switching part so that each of the plurality of voltage transducers (3a-3e) is connected to only one line of any of the plurality of the DC power output lines (6A-6C); and the controller controls the switching part such that a first voltage transducer in the plurality of voltage transducers (3a-3e) which is connected to a DC power-supply device having a relatively high output voltage is connected to a DC power output line having a relatively high set voltage, and a second voltage transducer in the plurality of voltage transducers which is connected to a DC power-supply device having a relatively low output voltage is connected to a DC power output line having a relatively low set voltage.