Precoding device and method in wireless communication system

The present invention relates to a precoder and a precoding method in a multi-user multi-antenna communication System. When a transmission part having a plurality of antennas transmits a plurality of signals to a receiving part having an antenna, the precoder and the precoding method using the same prevents System performance degradation caused by interference signals and efficiently reduces transmission power while changing the constellation rotary angle. When the power is controlled by using the precoder, the System performance is enhanced while not damaging the structural gain of the existing multi-user multi-antenna precoder.