To provide a travelling device having high traveling accuracy, with simple prior preparations, to safely and quickly execute integrity check, painting, processing, and working or the like at a place such as a high or narrow place and the place where work environment is dangerous, etc., in a large-sized structure like a boiler, a facility related to nuclear power, a chemical plant, and a ship, etc.

The travelling device is provided with a plurality of road gripping parts capable of gripping on and detaching from a run surface, caterpillars 2, 3, and a body 1 supporting the road griping parts and a running part. Imaging devices 4, 5 arranged on the body 1, receives a luminous flux 22 from a laser light source 21 projecting the luminous flux 22 which is from the outside of the travelling device and parallel to a planned run road of the travelling device. The luminous flux divided into two directions with beam splitter 8 having an irradiation surface at an angle of 45 degrees from the luminous flux 22, are reflected respectively, then respective reflected images are imaged on two screens 6, 7 with the imaging devices 4, 5. By comparing images imaged with the imaging devices 4, 5, there are detected a deviation between an actual road and the planned road, and the deviation between an actual run direction and a planned run direction with respect to the travelling device, to control so that the travelling device keeps the planned road. Therefore, the travelling device can run with high traveling accuracy.