The principal is an educational leader at the micro level who carries out management functions, including planning, organizing, mobilizing and controlling. The leadership style of the principal greatly influences an organization he leads. The objectives of this study are: (1) to analyze the effectiveness of the principal's leadership style in elementary schools (2) to analyze the effectiveness of the principal's leadership style in improving school performance in elementary schools. (3) Analyze the effectiveness of the principal's leadership style in improving school achievement in elementary schools. The results showed that (1) the level of the principal's leadership style was categorized as effective on school performance and achievement, (2) the principal's leadership style had a positive effect on school performance, (3) the principal's leadership style had a positive effect on school achievement. There is a relationship between the principal's leadership style and the improvement of performance and achievement in the Korwilcam Dindik East Purwokerto elementary school of 23,2% % (school performance) and 36,2% (school achievement). While the remaining 76,8 % and 63,8% % are the effective contributions that come from various factors or variables not included in the regression model equation obtained.