It is an object of the present invention to provide a reference signal transmitting method, a mobile terminal apparatus and a base station apparatus capable of reducing influences on a PDCCH even when performing transmission control over an aperiodic reference signal for measuring channel quality. Downlink control information corresponding to each component carrier in which transmission control information of a reference signal for measuring channel quality is set is aggregated and assigned to a downlink control channel of a specific component carrier for a mobile terminal apparatus that performs radio communication in a system band containing a plurality of component carriers and transmitted, and when the mobile terminal apparatus controls transmission of the reference signal for measuring channel quality based on the transmission control information of the reference signal for measuring channel quality included in the received downlink control information, the downlink control information corresponding to each component carrier includes a bit field in which identifier information of the component carrier is set and the transmission control information of the reference signal for measuring channel quality is set in the bit field.