Disclosed are a method and apparatus for transceiving data for a multimedia transmission system. The method of the present invention comprises the steps of: inputting a second data unit consisting ofone or more first data units from an encapsulation-function layer; analyzing the header information of the second data unit with a view to forming payload header information including a payload type and component information; forming one or more payloads from the second data unit in accordance with the sizes of the first data units; combining pieces of payload header information relevant to each payload with a view to forming a multimedia data packet; and transmitting the multimedia data packet to a counterpart entity. The payload includes at least one payload element, the type of which is selected from among a first type including one first data unit, a second type including header information of one first data unit, a third type including header information of one first data unit and a portion of data, or only a portion of data, a fourth type including header information of the second data unit, and a fifth type including the entirety of the second data unit.