The purpose of this study was to analyze effectiveness of private lessons on academic achievement. To conduct the purpose of the this study, the following research problems were established. First, to compare the effectiveness of private lessons perceived by subjects(students, college students, and private lecturers). Second, to analyze the effectiveness of private lessons in academic achievement, and to identify the degree of effectiveness in its variables. The sample consisted of 1,490 fifth grade(468), eighth grade(513), university students(316), and private lecturers(193) in Taegu, Korea. The instrument used were questionnaire and twice of academic achievement tests. The results of this study were as following; First, there were significant differences in the subjects' perception of the effectiveness of private lessons among the subject groups(students, college students, and private lecturers). But most of them took cognizance of the effectiveness of private lessons. Second, the influence of private lessons on academic achievement was found to be lower level students but not found to be higher level students. When family background variables were controlled, academic achievement variance accounted private lessons was a little. The important variables of private lessons which had significant influence to academic achievement were duration and term of private lessons.