This study is to analyze: (1) The effect of achievement motivation on freestyle swimming achievement. (2) The effect of self-confidence on freestyle swimming achievement. (3) The influence between achievement motivation and self-confidence on freestyle swimming achievement. This type of research is quantitative with an ex post facto approach. The population in this study were high school students in Yogyakarta. Researchers did not examine the entire population, the sampling technique used random sampling totaling 150 students. The instrument used was a questionnaire. Data analysis techniques using ANOVA analysis. The results showed that (1) There is a significant influence between achievement motivation on freestyle swimming achievement, with a p-value of 0.000 < 0.05. (2) There is a significant influence between self-confidence on freestyle swimming performance, with a p-value of 0.000 < 0.05. (3) There is a significant influence between achievement motivation and self-confidence on freestyle swimming performance, with a p-value of 0.000 < 0.05.