It is an object of the present invention to adequately report the SRS transmission timing and SRS parameters to a mobile terminal apparatus, when an aperiodic SRS is adopted, and efficiently use radio resources to be used for SRS transmission. A radio base station apparatus that reports SRS transmission control information to a mobile terminal apparatus and controls transmission of an SRS by the mobile terminal apparatus, and the radio base station apparatus has an SRS setting section that selects bit information to report to the mobile terminal apparatus, from a table having bit information to indicate not to trigger the SRS and bit information to indicate to trigger the SRS using a default SRS parameter, and a reporting section that reports the bit information for the mobile terminal apparatus using a downlink control channel.