The present specification provides a method for transmitting data of a machine type communication (MTC) device. The method for transmitting data of an MTC device comprises the steps of: receiving a mobility management (MM) latency timer from a mobility management entity within a network; operating the MM latency timer; determining whether data to be transmitted is generated before the expiration of the MM latency timer; and transmitting the data to be transmitted through an uplink NAS message even though the MM latency timer has not expired when the data to be transmitted is generated.