This study seeks to use the law sociological system model, to define the internal and external environmental changes that influence decisions of teacher appeals, and to analyze time-series trends of teacher appeals. This study analyzed appeal cases for 21 years from 1991 to examine number of lawsuits and relief rates by year. As a result, overall, in the case of the 1990s, the relief rates changed irregularly. However, after 2000, overall relief rates declined. This result was discussed to come from the societal request for responsibility of teachers and schools. It was suggested that, to achieve the original objective of appeal system for teachers, there should be a change toward the legal stability.