The present description discloses a service request method. The service request method comprises the steps of: increasing a counter whenever a service request message has been transmitted multiple times to a first network node in a first public land mobile network (PLMN), but an acceptance message has not been received by the time a first timer expires; comparing the counter value with an upper threshold value; and running a second timer if the counter value is equal to or greater than the upper threshold value, wherein the transmission of the service request message can be prevented until the second timer expires.