A method for transmitting, by user equipment, a PDU session establishment request includes: receiving a session management message based on an SSC mode from an SMF through an AMF in a state in which a back-off timer associated with a DNN-based congestion control is in operation, wherein the session management message is associated with a DNN to which the DNN based congestion control is applied; and transmitting a PDU session establishment request to the AMF for establishment of a new PDU session associated with the DNN on the basis of the session management message. The PDU session establishment request includes information for preventing rejection of the PDU session establishment request, and the information for preventing the rejection may be used to make the AMF ignore the DNN-based congestion control and transmit the PDU session establishment request to the SMF associated with the new PDU session.