To easily and accurately perform aiming control by providing a level correcting means for received signals and controlling the direction of an antenna to detect the peak point of the level corrected received signal.

At the center of front part of a vehicle 1, a supporting member 2 is installed so as to be vertically and laterally inclined while relatively and laterally juxtaposing plural antennas with prescribed directivity in advance. A correction processing part 5 is provided for correcting the level of received signal of a channel corresponding to the central antenna so as to sharpen the level characteristics of the received signal. A beam is emitted from the specified antenna among the plural antennas juxtaposed on the supporting member 2. Then, aiming is performed by controlling the direction of the supporting member 2 through a control mechanism 3 while watching the level of the received signal through a meter 4 so that the level of the received signal due to a reflected wave from a target 6 can become a peak.