The present invention relates to communicating control information in a mobile communication system, by which new control information can be transmitted more quickly. The present invention comprises transmitting a first data block comprising control information for transmitting first data when no resources for the transmission of the first data are available, receiving second data from an upper layer to be transmitted, wherein the second data has a higher priority than the first data, and transmitting a second data block comprising updated control information for transmitting the first and second data when no resources for the transmission of the first and second data are available.