An extraction unit (101) extracts as a stationary object-detection point, a detection point on a stationary object among a plurality of detection points around a vehicle (200), the plurality of detection points being detected by an outside-detection sensor (501) at a plurality of detection timings. A grouping unit (105) groups two or more stationary object-detection points deduced as detection points on a same stationary object, among a plurality of stationary object-detection points extracted by the extraction unit (101) at the plurality of detection timings.