A control device for a power converter equipped with a plurality of switching elements (S1 to S4), comprising: a drive control circuit disposed in correspondence with each of said plurality of switching elements for controlling a driving speed of a control electrode of a corresponding switching element; and a control circuit configured to select (i) a first mode in which each of the plurality of switching elements is controlled off independently from other switching elements and (ii) a second mode in which each of said plurality of switching elements is paired with another switching element connected in series and controlled off concurrently with the paired switching element, wherein said power converter is configured to perform a DC voltage conversion between a power line electrically connected to a load and a first DC power source and a second DC power source (10, 20) so as to control an output voltage (Vo) on said power line, said plurality of switching elements (S1 to S4) includes a first switching element which is electrically connected between said power line and a first node, a second switching element which is electrically connected between said first node and a second node, a third switching element which is electrically connected between said second node and a third node electrically connected to a negative terminal of said second DC power source, and a fourth switching element which is electrically connected between said third node and a negative terminal of said first DC power source, said power converter further includes a first reactor which is electrically connected between said second node and a positive terminal of said first DC power source, and a second reactor which is electrically connected between said first node and a positive terminal of said second DC power source, wherein in the second mode, the first switching element is paired with the second switching element and the third switching element is paired with the fourth switching element, said drive control circuit is configured to set said driving speed higher in said second mode than in said first mode. a drive control circuit disposed in correspondence with each of said plurality of switching elements for controlling a driving speed of a control electrode of a corresponding switching element; and a control circuit configured to select (i) a first mode in which each of the plurality of switching elements is controlled off independently from other switching elements and (ii) a second mode in which each of said plurality of switching elements is paired with another switching element connected in series and controlled off concurrently with the paired switching element, wherein said power converter is configured to perform a DC voltage conversion between a power line electrically connected to a load and a first DC power source and a second DC power source (10, 20) so as to control an output voltage (Vo) on said power line, said plurality of switching elements (S1 to S4) includes a first switching element which is electrically connected between said power line and a first node, a second switching element which is electrically connected between said first node and a second node, a third switching element which is electrically connected between said second node and a third node electrically connected to a negative terminal of said second DC power source, and a fourth switching element which is electrically connected between said third node and a negative terminal of said first DC power source, a first switching element which is electrically connected between said power line and a first node, a second switching element which is electrically connected between said first node and a second node, a third switching element which is electrically connected between said second node and a third node electrically connected to a negative terminal of said second DC power source, and a fourth switching element which is electrically connected between said third node and a negative terminal of said first DC power source, said power converter further includes a first reactor which is electrically connected between said second node and a positive terminal of said first DC power source, and a second reactor which is electrically connected between said first node and a positive terminal of said second DC power source, a first reactor which is electrically connected between said second node and a positive terminal of said first DC power source, and a second reactor which is electrically connected between said first node and a positive terminal of said second DC power source, wherein in the second mode, the first switching element is paired with the second switching element and the third switching element is paired with the fourth switching element, said drive control circuit is configured to set said driving speed higher in said second mode than in said first mode.