A power controller configured to be connected to a load and a plurality of power supplies (I1 to In) which are configured to supply electric power, the power controller comprising: - a plurality of switching elements (S1 to Sn) which are provided in one-to-one is correspondence with the plurality of power supplies, and each of which is configured to switch on or off to switch between supplying and stopping supplying the load with electric power from a corresponding one of the plurality of power supplies; - a processing unit configured to compute an operation amount for adjusting an amount of electric power supplied to the load; - a signal generator configured to determine, for each control cycle of a plurality of successive control cycles, a switching element count and a duty ratio so as to generate the computed operation amount over each control cycle, the switching element count indicating a total number of switching elements to be turned on among the plurality of switching elements for a portion of the control cycle, the duty ratio indicating the percentage of the total length of the control cycle corresponding to said portion, wherein the number of switching elements to be turned on during the rest of the control cycle is decreased by one with respect to the switching element count, and - configured to generate a drive signal for driving the plurality of switching elements successively, based on the switching element count and the duty ratio, characterized in that: the plurality of switching elements are numbered different from one another, and the signal generator is configured to select from among the plurality of switching elements a switching element to be first turned on, based on the switching-element count, configured to determine the switching elements to be turned on in forward or reverse order of the given numbers, the forward or reverse order starting from the switching element to be turned on, and configured to change, when the signal generator determines that the switching-element count is to be increased or decreased, the switching element to be first turned on to another switching element among the plurality of switching elements in the forward or reverse order, respectively, and wherein as the switching-element count decreases, the signal generator is configured to drive off a switching element that has the longest on-time among switching elements being on. - a plurality of switching elements (S1 to Sn) which are provided in one-to-one is correspondence with the plurality of power supplies, and each of which is configured to switch on or off to switch between supplying and stopping supplying the load with electric power from a corresponding one of the plurality of power supplies; - a processing unit configured to compute an operation amount for adjusting an amount of electric power supplied to the load; - a signal generator configured to determine, for each control cycle of a plurality of successive control cycles, a switching element count and a duty ratio so as to generate the computed operation amount over each control cycle, the switching element count indicating a total number of switching elements to be turned on among the plurality of switching elements for a portion of the control cycle, the duty ratio indicating the percentage of the total length of the control cycle corresponding to said portion, wherein the number of switching elements to be turned on during the rest of the control cycle is decreased by one with respect to the switching element count, and - configured to generate a drive signal for driving the plurality of switching elements successively, based on the switching element count and the duty ratio, the plurality of switching elements are numbered different from one another, and the signal generator is configured to select from among the plurality of switching elements a switching element to be first turned on, based on the switching-element count, configured to determine the switching elements to be turned on in forward or reverse order of the given numbers, the forward or reverse order starting from the switching element to be turned on, and configured to change, when the signal generator determines that the switching-element count is to be increased or decreased, the switching element to be first turned on to another switching element among the plurality of switching elements in the forward or reverse order, respectively, and wherein as the switching-element count decreases, the signal generator is configured to drive off a switching element that has the longest on-time among switching elements being on.