A to-be-charged apparatus, including: a built-in battery; a plug connectable to a jack included in a data storage apparatus capable of storing data and a jack included in a charging adapter; a drive unit that is capable of acquiring the data from the data storage apparatus while the plug is connected to the jack of the data storage apparatus and is driven by power supplied from the built-in battery; and a circuit that includes a data line for transmitting the data, which is connected between the plug and the drive unit, and supplies, when a connection of the plug to the jack of the charging adapter is detected by a detection switch included in the charging adapter connected to a power supply apparatus, a charge from the charging adapter to the built-in battery using the data line.