To level power consumption while also restricting reduction in convenience.

A power leveling method executes various processes by a computer, the processes involving collecting, for each of plural information processing devices, a history of changes in states of connection to a commercial power supply and recording the history in a history recording unit; identifying, on the basis of the history recorded in the history recording unit and for each of the information processing devices, a connection time zone during which they are connected to the commercial power supply; calculating an overlapping time between the connection time zone and a time zone during which the amount of power consumption was below a prescribed value as recorded in a transition recording unit; and selecting, in decreasing order of the overlapping time, an information processing device which is to be started using a battery stored in itself.