Packet transferring method and device

A packet transmission method and a device are provided to prevent an occurrence of jitter of message in cable modem terminal system. A plurality of packet is received from a second layer which is the higher layer of the physical layer(S100). A packet including a sync message is detected from a plurality of packets(S300). The time information for the sync is received from the second layer(S400). The time information is inserted into the sync message(S500). A plurality of packet is transmitted with a predetermined transmission rate(S600).