Fuente: Wipo "digitalization" A memory card (1001) having a playback function is adapted for connection with a digital signal source of a digital information system in receiving/delivery of a digital signal and has a memory for storing a specified digital signal and reproducing a digital signal stored independently. A secondary battery is built in the memory card, which is charged by a power supply on the side of a terminal device (100) when the memory card is connected to the terminal device.