There is severe difference in weekly teaching hours among teachers, especially of elementary and secondary level in Korea. The average teaching time of element school teachers is 25.7 hours, ranging from 25.0 to 32.0 hours. The average of middle school teachers is 19.5 hours, ranging from 12.0 to 27.0 hours. The average of high school teachers is 17.6 hours, ranging from 10.7 to 24.0 hours. The government is examining an introduction of new innovational policies for remedying the unequal work condition. Regulation of the optimal weekly teaching time(OWTH), recruitment of class teachers, improvement of allocating standard, etc. are mentioned as the new policies. This study is aimed to suggest the OWTH with procedures and formula to get it. The contents of study are composed of ① analysis of the current average teaching hours and need of optimal teaching hours, ② analysis of some cases in foreign countries, ③ development of procedures and formula to obtain the OWTH, and ④ suggestion of the OWTH by school level. In this study, the OWTH is defined as 'the duty hours of teachers teaching in class for a week, induced from the optimal ratio of teaching hours to working hours per week to guarantee the quality of instruction'. The optimal teaching time is obtained from the following formula. The standard average teaching hours is defined as 'average hours in charge of teaching per week and obtained from the following formula. In this study, the OWTHs of three cases are suggested. Firstly, 25.8 hours are presented for elementary school teachers, 19.6 hours for middle school teachers, and 17.7 hours for high school teachers as the OWTH in the present educational condition. Secondly, 24.5 hours are calculated for elementary school teachers, 18.7 hours for middle school teachers, and 17.0 hours for high school teachers as the OWTH after recruiting new teachers to fill up the present deficiency. Lastly, the OWTH corresponding to continuous reduction of class size can be obtained easily. In this study, it is emphasized that the OWTH is very closely related to class size, the number of teachers in charge of teaching, and duty learning time of student. Therefore, the OWTH should be determined after examining their correlations in the present educational condition. Of course, a financial support policy by the government should be accompanied for stable fixation and continuous decrease of the OWTH.