PURPOSE: To automatize the detection of a small target with easy discrimination of an area tending to generating a number of clutters from other areas by dividing trapping areas into several parts in addition to a plurality of reference levels for detection.

CONSTITUTION: Various signals received among transmitted pulses from a radar 1 are arranged on a position coordinate (distance coordinate: R, azimuth coordinate: θ, and detection reference value: TN) of a target obtained through a digitizer circuit 2 and then, sent to a gate checking circuit 3. On the other hand, a gate generation circuit 4 generates signals to divide trapping area 7W14 into several parts in terms of the distance: R and the azimuth: θ synchronizing the transmission pulses and sends them to the circuit 3. The circuit 3 discriminates the area of the target and sends the results to a memory device 5 as added to a target position coordinate data. The memory device 5 adds the data together for each area in terms of a detection level. When the results are above a preset clutter value for each area, those detected by the higher detection reference value for the area involved are taken in as target and the corresponding data are indicated.