Nowadays, the frequent occurrence of sinkholes, a natural disaster, has caused damage in both lives and facilities. Therefore, the geophysics investigation by using electrical resistivity method was performed at the sinkhole area of Rajaprajanugroh School 42, Khlong Khut Subdistrict, Mueang Satun District, Satun Province, to study the geological structure and to assess the risk of possible sinkholes. The visibility of a sinkhole which has a circular shape about 2.5 metres diameter and 2 metres deep, characterized by sand mixed with gravel layer as a result of accumulation due to the construction in the area allowed us to run 2 geophysical survey lines across the sinkhole area. It was found based on resistivity distribution in the subsurface that the overburden consisted of sandy soil mixed with gravel. This layer overlies the water saturated zone and limestone layer. It is interesting to note that, possible cavities appear to develop beyond 20-60 metres of the survey line, and there might be a risk for the occurrence of sinkholes.