A battery pack that includes a data storage unit capable of storing data processed with an electronic device and a data control unit for controlling reading, writing, deleting, and duplicating of data in the data storing unit. A data communication unit for transmitting and receiving data controlled by the data control unit. A charger includes a data communication unit for transmitting and receiving data with the battery pack via a communication terminal and a data operating unit for sending control signals instructing data reading, writing, deleting, and duplicating of data in the data storage unit of the battery pack via the data communication unit. A data reproducing unit for reproducing the data obtained via the data communication unit. This provides a simple battery pack which can record data handled by an electronic device to which the battery pack is mounted, and a charger enabling easy operating of the recorded data.