A communication method for sounding reference signal transmission is provided. A communication method of a user equipment in a mobile communication system in which a base station apparatus schedules a physical uplink shared channel in an uplink component carrier by using a downlink control information format, the method comprising: receiving, from the base station apparatus, the downlink control information format including first information which instructs to transmit sounding reference signal and second information which indicates the uplink component carrier in which the physical uplink shared channel is scheduled by the downlink control information format, transmitting, to the base station apparatus, sounding reference signal on the uplink component carrier indicated by the second information in case that the first information is detected.