The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for handling of a RRC connection request message of a remote UE by a Relay UE in wireless communication system, the method comprising: receiving NAS information for establishing RRC connection of the remote UE from a remote UE which is configured to connect to the relay UE via sidelink in state that both of the remote UE and the relay UE are in RRC idle states, transmitting a RRC connection request message with an identity of the remote UE to an eNB, when a NAS layer of the relay UE triggers only service request for the remote UE; transmitting a RRC connection setup message for the remote UE to the remote UE;