［Objective］ The Objective of this study was to clarify the relationships among physical fitness, academic achievements, psychological stress scale scores and lifestyles (eating breakfast, sleeping time, time spent for watching television and game). It was done for the subjects of 175 junior high school students in 2014.
［Methods］ We used the following statistical analyses：the Pearson product-moment correlation coefficient, the one-way analysis of variance, the Bonferroni's method for performing multiple comparisons, the chi-square test by cross tabulation and the logistic regression analysis.
［Results］ the primary results were as indicated below.
1) Academic achievements of boys with higher physical fitness were a little high, and their stress degree was low. They could also perform well on different physical activities such as sit up and standing jump.
2) Academic achievements of those who have breakfast everyday were also high, and the stress degree was low. The stress degree of those whose sleeping time a day is less than 6 hours was relatively high.
3) According to the logistic regression analysis, among the factors that influenced academic achievements, physical fitness and breakfast showed large influences.
As a result, it seems that it is preferable to develop the class of the health education and physical education that considers the physical strength improvement and the breakfast intake.
