To surely suppress unnecessary waves input from an intersection direction of antenna patterns of a main system and an SLC(side lobe canceller) system and a null point direction of a side lobe area.

The apparatus is provided with a comparator 6 to which a receiving signal of a main system is input and which judges whether or not an unnecessary wave is input, a comparator 3 to which receiving signals of the main system and an SLC system are input and which judges whether or not a direction of the unnecessary wave is a side lobe direction, and hold circuits 4, 7 which holds outputs from the comparators temporarily. An ON/OFF controller 9 judges based on outputs of the hold circuits 4, 7 whether or not a side lobe process is to be carried out. Even when judgments by the comparators 6, 3 frequently switch, the ON/OFF controller 9 can output judge results stably because the judge results of the comparators are held at the hold circuits 7, 4. An SLC processor 10 can restrict unnecessary waves surely.