An apparatus for transmitting an uplink signal and method thereof are disclosed, by which an uplink signal can be efficiently transmitted in a wireless communication system. The present invention includes receiving a downlink control information (DCI) used for PUSCH (physical uplink shared channel) scheduling, the DCI including an information for resource block allocation, an information for a channel status information request and a plurality of MCS (modulation and coding scheme) informations for a plurality of transport blocks and if a condition is met, transmitting a channel status information only on the PUSCH without a transport block for UL-SCH (uplink shared channel). Moreover, the condition includes a case that: only one transport block is enabled, the MCS information for the enabled transport block indicates an MCS index 29, the information for the channel status information request indicates 1, and the number of allocated resource blocks is equal to or smaller than 4.