To make returning to a home provider network early while saving power consumption by controlling an interval when a home signal from the base station of the home provider is scanned based on the change of a receiving level of a roaming signal in a roaming destination provider network.

A radio equipment part 50 receives a signal from a base station of roaming destination provider network in a waiting operation state during roaming. A receiving level detection recording part 30 compares a receiving level detected this time with a preceding level and stores change quantity in a change quantity recording table 31. When the change quantity of a receiving level is equal to or more than a preliminarily defined standard value, the part 50 is made to carry out home network scan processing. When a receiving level is low as a result of the home network scan processing, it waits at a roaming destination again. In such a case, a roaming controlling part 10 refers to the table 31 and sets the scan interval of a timer part 20 to a long interval when the change quantity of a receiving level is small.