An apparatus configured to assist in driving of a vehicle in order to cause the vehicle to follow a target track, the apparatus comprising: a first traveling track determining section that determines a first traveling track along which a first vehicle is able to travel based on road infrastructure; a second traveling track determining section that determines a second traveling track along which the first vehicle is able to travel based on the traveling track of a second vehicle that precedes the first vehicle; a deviation information storage section that stores deviation information about deviation between the first traveling track and the second traveling track such that the deviation information corresponds to traveling positions of the vehicles; and a target track formation section that forms, based on either the first traveling track or the second traveling track, a target track that the first vehicle is caused to follow, the apparatus being characterized in that when a base for formation of the target track is switched between the first traveling track and the second traveling track, the target track formation section forms the target track by calculating the target track based on: the deviation information acquired when the base for formation of the target track is switched between the first traveling track and the second traveling track, and the travelling track, of the first traveling track and the second traveling track, to which the base for formation of the target track is switched. a first traveling track determining section that determines a first traveling track along which a first vehicle is able to travel based on road infrastructure; a second traveling track determining section that determines a second traveling track along which the first vehicle is able to travel based on the traveling track of a second vehicle that precedes the first vehicle; a deviation information storage section that stores deviation information about deviation between the first traveling track and the second traveling track such that the deviation information corresponds to traveling positions of the vehicles; and a target track formation section that forms, based on either the first traveling track or the second traveling track, a target track that the first vehicle is caused to follow, the apparatus being characterized in that when a base for formation of the target track is switched between the first traveling track and the second traveling track, the target track formation section forms the target track by calculating the target track based on: the deviation information acquired when the base for formation of the target track is switched between the first traveling track and the second traveling track, and the travelling track, of the first traveling track and the second traveling track, to which the base for formation of the target track is switched. the deviation information acquired when the base for formation of the target track is switched between the first traveling track and the second traveling track, and the travelling track, of the first traveling track and the second traveling track, to which the base for formation of the target track is switched.