The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for changing a connection by a user equipment (UE) connected with a relay UE through a device to device (D2D) link in a wireless communication system, the method comprising: receiving information on a threshold value through a broadcast signaling; measuring a quality of a channel from a cell; establishing a radio resource control (RRC) connection with the cell when the measured quality is higher than the threshold value; and releasing the D2D link with the relay.