The present invention relates to a method for controlling system overload in a wireless communication system. The method comprises: a first step in which a mobility management entity (MME) that has received a tracking region update request message from a first terminal transmits a location update request message to a home subscriber server (HSS); a second step in which, if the HSS has determined that a system overload has occurred, the HSS sets MME-backoff time for preventing the transmission of a request message to the HSS, and transmits a location update rejection message including said MME-backoff time to the MME; and a third step in which the MME drives a backoff timer corresponding to said MME-backoff time and rejects a TAU update request message from a terminal received prior to the completion of the driving of the backoff timer.