A charge/discharge control device capable of increasing the lifetime of a storage portion while suppressing effects of fluctuation in power generated by a power generator on a power grid is provided. This charge/discharge control device is so formed as to start charge/discharge control of the storage portion if an amount of change in power detected by a power detection portion detecting power passing through a prescribed portion of a line between the power generator and the power grid is at least a prescribed amount of change when the detected power changes from first power to second power while the detected power does not return to power in the vicinity of the first power from the second power within a first period from a time point when the detected power changes from the first power to the second power.