A mobile station is disclosed including a processor that, in Carrier Aggregation using component carriers that are under the control of a master radio base station and a secondary radio base station, when a plurality of random access procedures are started, and when simultaneous transmission of random access preambles occurs in the plurality of random access procedures, performs a ramping control on a transmission power of a random access preamble in a random access procedure that is assigned priority and does not perform the ramping control on a transmission power of a random access preamble in the random access procedure other than the random access procedure that is assigned priority, a receiver that receives signals from the master radio base station and the secondary radio base station, and a transmitter that transmits signals to the master radio base station and the secondary radio base station.