Provided is an automatic steering system that performs turn control on a vehicle to cause the vehicle to efficiently transfer from a previous route (Ls) to a subsequent route (Ln). An automatic steering system includes: a first steering control module (61) to perform steering control for first turn travel on a vehicle to cause the vehicle to leave a previous route (Ls) and head for a subsequent route (Ln)； a second steering control module (62) to perform steering control for second turn travel on the vehicle to cause the vehicle to enter the subsequent route； a third steering control module (63) to perform steering control for shift travel on the vehicle to cause the vehicle to shift from the first turn travel to the second turn travel； a virtual turning circle calculation module (67) to calculate a virtual turning circle (VC) to be used as a target route for the second turn travel； and a tangent calculation module (68) to calculate, as a target route for the shift travel, a tangent extending from a vehicle body reference point (Pv) in the first turn travel to the virtual turning circle (VC).
