A method and apparatus for controlling an uplink transmission power in a mobile station of a mobile communication system. The method includes transmitting uplink data in a first transmission interval, receiving a transmission power control information over a downlink control channel, and determining a transmission power of uplink data to be transmitted in a second transmission interval. The transmission power is determined based on the received transmission power control information and a transmission power of the uplink data transmitted in the first transmission interval. The first transmission interval and the second transmission interval are included in a same Hybrid Automatic Retransmission reQuest (HARQ) process.