When material transport was automated on a building construction site, in a conventional travel tape guide system, it was necessary to replace the tape when it became soiled or when changes were made to a travel route. As a result, the usage efficiency of a material transport vehicle could not be improved on the site due to the fact that changes are made to work floors as demanded by construction schedules. According to this invention, there is provided a sign which is easy to move and which is installed at a turning point or an unloading point on a work floor transport route. An image of the sign is obtained by an imaging device on an autonomous guided vehicle and operating instructions are recognized by image processing. This makes it possible to automate the setting of routes and the control of the vehicle.