The purpose of this study is to develop and propose a highly valid and reliable diagnostic tool that can measure the level of digital utilization competencies of adults in Korea. The factors of digital utilization competencies derived through literature review and expert review were digital device use, ethics/security, and real-life use, and a total of 10 preliminary questions were derived. After confirming the preliminary questionnaire items according to the results of the Delphi survey with 10 experts, a survey of 1,000 adults in Korea was conducted. As a result, eight items of three factors were confirmed through exploratory factor analysis and confirmatory factor analysis, and all three factors were found to have AVE values higher than the coefficient of determination and greater than .5, securing the validity of discrimination. As a result of the reliability verification, Cronbach's value of the entire digital utilization competencies diagnosis tool was .8, and the three factors showed .5 or more, respectively. A path analysis between the factors of digital utilization competencies and subjective life satisfaction was conducted by verifying the reference validity, and it was found to have a statistically significant positive (+) correlation. Finally, as a result of the measurement identity verification, it was confirmed that the tool can be used regardless of gender. Finally, practical implications for utilizing the diagnosis tool of adults and measures to foster talented people with digital utilization competencies in the future were provided.