A method and a device for allocating a persistent resource in a mobile communication system are provided. In a broadband mobile communication system such as an IEEE 802.16m system, when allocating a persistent resource, because the terminal may transmit a Hybrid Automatic Repeat reQuest (HARQ) sub packet in a continuous frame without receiving the HARQ feedback from the base station, uplink coverage may be extended. When persistent resource allocation is used in uplink, the base station may transmit an HARQ sub packet without receiving the HARQ feedback during the persistent resource allocation period to improve uplink coverage of an allocated persistent resource.