1. A method for transmitting aperiodic channel state information (CSI), the method performed by a user equipment (UE) and comprising: receiving an uplink downlink control information (DCI) format; and transmitting aperiodic CSI through a Physical Uplink Shared Channel (PUSCH) if a CSI request field included in the uplink DCI format is set to trigger an aperiodic CSI report, wherein the CSI request field is either a 1-bit field or a multi-bit field, wherein, when the UE is configured with only one cell, the 1-bit field applies to the UE, and wherein, when the UE is configured with more than one channel state information-reference signal (CSI-RS), the multi-bit field applies to the UE.