In order to detect an object by discriminating the object in accordance with the state of the object, a detection device comprises: an identifying unit configured to identify whether a human included in a plurality of frame images of a moving image is a pedestrian; a determining unit configured to determine, for notifying, that the human is the pedestrian if the identifying unit identifies that the number of times the human is the pedestrian satisfies a predetermined condition; and a notifying unit configured to notify intrusion if the human determined as the pedestrian by the determining unit intrudes into an area preset for the moving image.