Disclosed are data transmission-reception system and data transmission method, in which a communication system includes: a first communication device for transmitting outgoing data including content identification data, transmitting party identification data, receiving party identification data, and date and time data; a second communication device for receiving the outgoing data and for transmitting content data identified by the content identification data to a receiving party identified by the receiving party identification data at a date and time corresponding to the date and time data; and a third communication device for receiving and reproducing the content data transmitted from the second communication device.