The essential feature of the present invention is the provision of a track transportation system in which a vehicle runs on a predetermined track, being automatically steered, having a simplified and lightweight structure so as to surely ensure a safety, and to be capable of carrying out efficient and high-speed operation. The track transportation system according to the present invention incorporates a steering mechanism for automatic steering by means of an M actuator, a protection guide rail laid on the track, protection guide wheels which travel together with the vehicle along the protection guide rail without making contact with the latter, and a control means for controlling automatic steering in accordance with a result of determination by a track data determining means for determining a straight portion, a curved portion, a turnout portion or the like of the track in view of vehicle position data, and steering caused by the protection wheels making contact with the protection guide rail.