A method and an apparatus for transmitting/receiving feedback in a mobile communication system are provided. The method includes transmitting, to a terminal, CSI feedback configuration information including feedback mode information, and information on a codebook configuration and a CSI-RS configuration; and receiving, from the terminal, CSI feedback information including a CQI and a PMI based on the feedback mode information. The feedback mode information indicates types of CSI feedback information. The information on the codebook configuration and the CSI-RS configuration includes a set of available precoding matrices and a first number and a second number associated with antenna ports of CSI-RS. A number of the antenna ports of CSI-RS is determined based on the first number and the second number associated with the antenna ports. The PMI indicates a precoding matrix included in the set of available precoding matrices. The CQI is obtained based on the CSI-RS associated with the number of antenna ports.