[en] Gas turbines operate under severe conditions such as high temperature and pressure. Thus, NDT technologies is critical to ensure the integrity of facilities. Conventional NDT methods to inspect parts of gas turbine are fluorescent penetrant inspection, magnetic particle testing, etc. These method has limits to identify flaws of gas turbine. In this study, eddy current testing was performed with the surface eddy current probe for the gas turbine 1'st stage bucket. Reference specimens is designed and made with EDM notches. We estimated the depth of the surface crack which is occurred in the 1'st stage bucket.