The purpose of this study was to investigate item goodness-of-fit of Scale, Rasch rating scale model was applied to 4 dimensions 20 items of the Sport Mental Power Scale(SMPS) in a sample of Golf player(n=405). An assumption to test Rasch Model, which is satisfaction of unidimensionality, is regarded through PCAR test, and WINSTEPS 3.65 program is used to test the goodness-of-fit of items. The results of this study were: First, 3-point rating category was appropriate for the SMPS instead of the existing 5-point rating category. Second, as a result of analyzing the goodness-of-fit of the items, 14 items of the SMPS were suitable, but 6 items were not. Third, the item reliability of person separation and the person reliability of item separation of the SMPS was acceptable.