The main purpose of this study was to investigate the relationships between students' study skills and their academic achievement in middle and high school. In order to achieve the purpose, the test of these skills was delveloped. It was consisted of 50 items in four elements of study skills; 1) self-management, 2) listening and participating in class, 3 completing assigment, 4) taking tests. The test was administrated to the sampled students(N=400) of middle and high schools in Pusan area. The findings of this were as follows; 1. There was significant relationships between the students' study skills and their academic achievement. 2. The level of study skills in high school students was a moderate higher than their academic achievement. 3 There was significant relationships between the male and female students, leaving skill. These findings suggest that the systematic use of particular study skills is responsible for the success of high-achieving students.