PURPOSE: To automatically monitor the abnormal approach of a traveling object such as an aircraft, a ship, etc., outside a rader coverage.

CONSTITUTION: An abnormal approach monitoring device 3 monitors the abnormal approach of the traveling object by having a filtering part 11 judging the approach of another traveling object with the crossing of a separation box by having the separation box showing an appropriation area excluding the approach of another traveling object in the direction of a traveling route based on traveling schedule data of the traveling object, a route judgement part 12 judging the kind of the traveling route of the traveling object and an abnormal approach judgement part 13 judging the presence/absence of the abnormal approach from vertical/horizontal intervals decided by the kind of the traveling route. Besides, the abnormal approach monitoring device 3 has a warning display part 14 visually displaying the traveling situation of all the traveling objects and the warning of the abnormal access of the traveling objects on a display 4.