Mobile station and mobile communication method

A mobile station comprising:

• a dedicated signaling reception unit configured to receive a dedicated signaling including a priority for a frequency or a group of frequencies of each radio access network;
• and
• a camp-on processing unit configured to select a camp-on cell based on the priority or a radio quality in each cell, wherein when a predetermined flag is set to the dedicated signaling received by the dedicated signaling reception unit, the camp-on processing unit is configured to select the camp-on cell based on the radio quality in each cell, from a plurality of cells that use a different frequency but reside within an identical radio access network, and to select the camp-on cell based on the priority included in the dedicated signaling, from a plurality of cells within a different radio access network;
• wherein when the predetermined flag is not set to the dedicated signaling received by the dedicated signaling reception unit, the camp-on processing unit is configured to select the camp-on cell based on the priority included in the dedicated signaling, from a plurality of cells that use a different frequency but reside within an identical radio access network.