A method for receiving a packet by a terminal in a mobile communication system including a base station providing a packet, and a terminal that discontinuously receives a packet from the base station in Discontinuous Reception (DRX) cycles each having an active period and a sleep period. The packet reception method includes receiving, from the base station, configuration information for a DRX service, including a DRX cycle length; setting, as a starting point of the DRX cycle, a point at which a first packet is received from the base station; receiving a packet from the base station for an active period at the beginning of the starting point; and transitioning to a sleep period and waiting for a next active period.