An automatic drive assist apparatus includes a storage, an own-vehicle position estimator, a route-information input device, a traveling route setter, and an automatic drive controller including a rerouting request determiner, a course comparator, and a course-change achievability determiner. The automatic drive controller causes an own vehicle automatically traveling along a traveling route determined by the traveling route setter. When the rerouting request determiner determines that a new traveling route is reconstructed in response to a rerouting request, the course comparator reads a candidate route of the new traveling route, compares the candidate route with the traveling route determined before the reconstruction, and determines whether a route change is set. When the route change is determined not to be achievable by the course-change achievability determiner, the automatic drive controller causes the own vehicle to keep automatically driving along the traveling route determined before the reconstruction.