TPC is appropriately operated in response to access method switching timing, an error is prevented from occurring in communication, and influence given to another cell due to transmission of unnecessary power is reduced.A base station apparatus which performs wireless communication with a mobile station apparatus while switching a plurality of kinds of communication method, transmits control information for performing transmit power control of the mobile station apparatus to the mobile station apparatus. The mobile station apparatus receives the control information for performing the transmit power control from the base station apparatus and determines a transmitted power according to the control information when switching the communication method.