Non-destructive testing (NDT) is a technique for evaluating internal and surface defects, material degradation, and structural integrity of an object without destroying it. In manufacturing, it is an indispensable process for product quality assurance, safety assurance, and reliability improvement, and is applied to a wide range of parts and products such as welds, castings, forgings, and composite materials. Typical methods include ultrasonic testing (UT), radiographic testing (RT), magnetic particle testing (MT), penetrant testing (PT), and eddy current testing (ET), each differing in its detection targets and applicable materials. Its value is demonstrated throughout the entire lifecycle, from quality control during the manufacturing process to final inspection of finished products, and even equipment diagnosis during operation.