The present disclosure relates to a 5G or pre-5G communication system to be provided for supporting a higher data transmission rate beyond 4G communication systems such as LTE. More specifically, a method for transmitting and receiving signals by a base station of a mobile communication system according to one embodiment of the present specification comprises: a step of determining whether to steer a traffic related to a terminal to a wireless LAN; a step for determining a traffic to be steered to the wireless LAN; a step for transmitting, to the terminal, a first message including information for an uplink transmission of the traffic to be steered; and a step for transmitting, to a gateway, a second message including information for a downlink transmission of the traffic to be steered. According to an embodiment of the present specification, in a network and a terminal using both a cellular and a wireless LAN, presented is a method for transferring, via an access network considering the signal strength between the terminal and each access network, a load condition of each access network, a policy of a provider etc., traffic which are sent and received by the terminal and the network.