There are approximately 10,000 road tunnels in Japan. Inspections of the road tunnels are conducted once every 5 years by human visual inspection based on the Road law enforcement regulations of Japan Ministry of land, Infrastructure, Transport and Tourism. However, presently the number of the inspection engineers are insufficient and the cost of the check is significantly high. In conventional crack inspection methods, engineers process the many images off site. But much effort is required to identify many cracks and dirt in the method. The authors have studied an automatic detection method for the crack positions by using high-resolution texture/depth images acquired by the mobile light-section method. We introduce the study-outline and the prototype devices we developed in this report. Furthermore we shows the results detected by our method using both concrete test samples and simulated real-size tunnel lining concrete.