The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for receiving a priority in a D2D communication system, the method comprising: receiving an RRC signal for configuring a radio bearer for relay packet reception with a downlink logical channel priority for the radio bearer; and configuring the radio bearer corresponding to the downlink logical channel priority based on the RRC signal, wherein a relay packet received from the radio bearer is transmitted to a second UE based on the downlink logical channel priority.