The present invention discloses a method of re-transmission of a lost MMT packet by a packet transmission apparatus. The method includes generating a media processing unit (MPU) based on a media fragment unit (MFU) and generating an MMT asset by encapsulating the MPU; generating an MMT packet based on the MPU included in the generated MMT asset; and transmitting the generated MMT packet, wherein the method further comprises adding, in a signaling message related to re-transmission of the MMT packet, delay_constrained_ARQ_flag to indicate whether or not the MMT packet transmission apparatus supports a delay-constrained automatic repeat request (ARQ) function.