Disclosed embodiments include a method and a device for transmitting UL packet based on QoS flow, the method including receiving uplink (UL) packet from an upper layer; checking whether a IP flow of the UL packet is matched to any of UL IP flow to QoS flow mapping defined in QoS rules configured to the UE; setting a QoS Flow ID of the UL packet to a special value if a IP flow of the UL packet is not matched to any of UL IP flow to QoS flow mapping defined in the QoS rules configured to the UE; and transmitting the UL packet with the QoS Flow ID set to the special value to a network via a DRB. The UE is capable of communicating with at least one of another UE, a UE related to an autonomous driving vehicle, a base station or a network.