In a surroundings monitoring apparatus (1), a front approaching object detection section (12) detects a front approaching object that is approaching the vehicle from ahead from among objects sensed bya front millimeter wave radar (20) (step Sl). An object specifying section (14) specifies the object which has been detected as the front approaching object by the front approaching object detectionsection (12) from among objects sensed by a rear millimeter wave radar (60) (steps S9 and SIl). A rear approaching object detection section (16) excludes the object specified by the object specifyingsection (14) from the objects sensed by the rear millimeter wave radar (60) to detect a rear approaching object that is approaching the vehicle from behind (step S12).