Provided is a method of controlling power of a downlink channel in a wireless communication system, the method including: transmitting at least one data to a user equipment; receiving feedback information for the data from the user equipment; and controlling downlink transmission power using the feedback information. It is possible to control the power without time delay and additional use of radio resources in a VoIP service which is responsible for satisfying a fixed transmission rate in real time. Moreover, it is possible to control the power without waste of control channels to perform PDCCH link adaptation.