PURPOSE: To make it possible to detect the azimuth of a radar radio wave with low pulse repeating frequency and to attain to enhance sensitivity without enlarging an apparatus, by operating an approximate azimuth and a detailed azimuth to an arrival radio wave.

CONSTITUTION: The antennae of an antenna group 10a corresponding through a receiver 3a are successively connected to the memory circuits of an approximate azimuth operating circuit 11a for definite time while antennae similarily corresponding through a receiver 3b are successively connected to memory circuits for a definite time. In this case, a demodulated level is stored in each memory circuit 5. When the change-over of change-over switches 2a, 4a and 2b, 4b is thoroughly completed, operators 8a, 8b respectively use two high level informations among level informations to calculate an approximate azimuth. In the next step, an operator 6 determines a detailed azimuth on the basis of each approximate azimuth information.