In a multi-directional antenna that is connected to a digital TV broadcast signal receiver, an RF amplifier in which its transmission gains are controlled is installed on the front of a tuner, a BER (BIT ERROR RATE) threshold is set as a reception determination standard to assess received images, and while auto-scanning, the amplification transmission gain level of the RF amplifier is controlled while changing in a phased manner to measure the BER value, and upon obtaining a BER value that is lower than the BER threshold, remaining scan and controlling transmission gains are stopped, and the receiving direction is determined. Thereby, by deleting scans in all directions in the adjustment of receiving directions for all channels, improving the reception sensitivity in a weak electric field, and determining the receiving direction by measuring and assessing the BER value, meaningless time for the direction adjustment can be saved, and the best reception condition can always be obtained quickly.