A mobile radio communication system having one or more relay stations and base stations, a gateway, an external device having a route selection function, and a policy control device which selects a main route and a sub route on the basis of residual resources in a radio communication device. The mobile station connected to one radio communication device can select another radio communication device having a large amount of residual resources as a new access point when the one radio communication device cannot be used, to prevent shortage of the radio resources. Also, it is possible to enable a process of selecting the radio communication device as a new access point to be omitted when switching one route to another by determining a sub route as the new access point when a main route is disconnected in advance, to shorten a service disconnection time.