A method for transmitting and receiving a signal in a packet data network gateway (PGW) of a mobile communication system according to an embodiment of the present specification comprises the steps of: receiving a first request message which includes an identifier of a terminal and is associated with a packet data network connection; sending a second request message to a policy and charging rules function (PCRF) server on the basis of the received first request message; and if quality of service (QoS) related information is included in a response message received in response to the second request message from the PCRF, performing a control associated with the packet data network connection on the basis of the QoS related information. In a wireless communication system using a PMIP according to the present invention, it is possible to generate a PDN connection in accordance with the default QoS.