A method that can measure the road density in the field is very effective in managing and maintaining road quality. However, the conventional density measurement method has a disadvantage that it is difficult to use in the field because it requires much time. In this study, road density measurement and underground facility exploration were performed using ground-penetrating radar (GPR). A value of 2.1–3.1 g/m3 was obtained through a road density test of the study site by measuring the road density. A pavement density profiler (PDP) is very efficient because values in the field can be checked more simply than by the conventional method of calculation through an indoor experiment. In addition, for exploring underground facilities, the water pipes of the study site were measured and their measured values were compared with the actual measured values. The accuracy of the underground facility exploration using GPR was 0.06–0.19 m. This means that the criteria for surveying underground facilities are satisfied. The use of GPR for underground facility surveying can enable the exact location and depth of piping to be recorded, which can greatly increase the efficiency of the work involved.