Method and apparatus for drx resume after up-link data transmission in mobile telecommunication system

A reverse data processing method of a terminal which performs a discontinuous receiving action in a mobile communication system and a device thereof are provided to control a sleeping section and an active section variably by considering whether reverse data is retransmitted, thereby more flexibly operating in discontinuous receiving mode. When reverse data is generated in a terminal which performs a discontinuous receiving action(305), the terminal demands transmission resource allocation by reporting a buffer situation to a base station(310). The terminal starts an active period(315). If final data satisfies one of two discontinuous receiving triggering conditions, the terminal receives control information which notifies of 'discontinuous receiving action resume' in an MAC(Medium Access Control) PDU(Packet Data Unit) for receiving the final data, and sends the control information(345). If transmission of the MAC PDU is completed, the terminal resumes a discontinuous receiving action(350).