A charging device comprises: a plurality of secondary batteries 11; and a charge and discharge control circuit 13, wherein at least either of: a plurality of thresholds each as a charge amount detection threshold; and a plurality of thresholds each as a discharge amount detection threshold are set, and each time the remaining battery level of a charge-side secondary battery 11 reaches the charge amount detection threshold and each time the remaining battery level of an other secondary battery 11 as a discharge-side secondary battery 11 reaches the discharge amount detection threshold, the charge and discharge control circuit 13 determines whether or not to perform switching between the secondary batteries 11 subjected to charging and discharging, depending on the remaining battery level of the charge-side secondary battery 11 and the remaining battery level of the discharge-side secondary battery 11.