In cold and snowy parts of Japan, most snow is removed from roads by mechanical snow removers, and to deal with roadside conditions and guarantee safe operation, these machines are normally operated by two people: an operator and an assistant. Work is in progress to develop automatic steering systems for snow removers in order to lighten the burden on snow remover operating staff and to reduce future labor requirements. This report describes an automatic steering system that incorporates three technologies: the lane marker system that has been developed in recent years as an ITS technology, RTKGPS technology, and GIS technology. This steering system has been developed for rotary snow removers: the type of snow remover considered to be the most difficult to operate. The report also evaluates the three control methods based on the results of corroborative testing done using actual snow removers and outlines problems with these control systems that must be overcome to establish a working system.