A radio communication apparatus includes a control unit that, if a radio access bearer (RAB) for a circuit switching domain is reconfigured between a dedicated channel (DCH) and enhanced uplink dedicated channel/High Speed Downlink Packet Access (E-DCH/HSDPA) and an RAB corresponded to RAB information exists as an established RAB and there exists no transparent mode (TM) radio bearer for a core network (CN) domain included in an information element of CN domain identity (ID), and at least one TM radio bearer is included in an information element of radio bearer (RB) information to setup, calculates a start value that is used on a new RAB.