An antenna driving device for a mobile communication terminal including a flat antenna and a receiver for receiving a radio signal through the flat antenna. The device has a flat antenna driver for shifting the direction of the flat antenna by predetermined steps; an RSSI detector for detecting the RSSI value of the received radio signal for each shifting step of the flat antenna; a position detector for detecting a position of the flat antenna through the flat antenna driver; a memory for storing the RSSI value detected for each step and the associated flat antenna positional information; and a controller for controlling the flat antenna driver and the RSSI detector, and for shifting the direction of the flat antenna to a position having the highest RSSI value by controlling the flat antenna driver. The flat antenna driver comprises a motor for shifting the direction of the flat antenna; and a driver for driving the motor under the control of the controller to shift the direction of the flat antenna.