A power control method of a base station in a wireless communication system based on Orthogonal Frequency Division Multiple Access (OFDMA) is provided for reducing power consumption by turning off the bias of the power amplifier for the duration of a symbol carrying no user data. The method includes checking scheduling information of radio resources, detecting a symbol carrying no user data, based on the scheduling information, and turning off a bias of the power amplifier for a symbol duration of the symbol carrying no user data. The transmission power control method is capable of reducing power consumption of the base station by turning off the bias of the power amplifier of the base station for the symbol duration in which no user data is transmitted.