PURPOSE: To prevent omission of a search beam by inserting data on a beam not yet scanned in a spare time part of a subsequent unit time, regarding the search beam of which beam scanning angle is an upper limit value or above.

CONSTITUTION: In a scanning angle limiting device 7, a beam scanning angle is determined as to an inputted search beam and the beam of which the scanning angle exceeds a prescribed upper limit value is outputted to a storage device 8 for a beam not yet scanned. In the storage device 8 for the beam not yet scanned, coordinate information on the inputted search beam and radar parameters thereof are stored and they are outputted to a correcting device 9 for the beam not yet scanned, in a subsequent unit time. In the case when the beam can be scanned in the unit time, a loss due to the scanning angle is computed, the radar parameters are corrected and the coordinate information and the radar parameters are outputted to a beam scanning sequence control device 5. In a spare time generating device 13, a spare time per unit time determined beforehand is generated and outputted to the beam scanning sequence control device 5.