Tanks for FRP materials used in the industrial field are composed of composite structures in which a resin and glass fibers are combined. The greatest advantage of FRP materials is its excellent chemical resistance, which makes them to store various chemicals or to keep the purity of the liquid in the container. In case of FRP material, the manufacturing method is different according to the manufacturer, and there are many cases where the FRP materials are manufactured by hand. In this study, non - destructive testing (NDT) of industrial tanks of FRP material was carried out using PAUT equipment. The PAUT equipment based on the UT non-destructive testing is capable of phased array arrangement, enabling comparative inspection in a multifaceted manner. In particular, in the case of the C-Scan mode, since the thickness and the signal are calculated through the 2D mode through designating the inspection area and the entirety of the corresponding section, it is easy to derive the defect and the state result through comparative analysis. In this study, non - destructive testing was carried out on about 150 (10 - 30 year old) FRP tanks in operation in actual industrial field. The thickness, fiber layer, pore, crack, and delamination test method were established through accumulated back data. However, the FRP material tanks differ in shape and internal structure depending on the manufacturing method, product company, and application, and various factors such as fiber porosity should be judged comprehensively. Therefore, data must be carried in advance.