This study aims to figure out relationships between school principal's Instructional
leadership, teacher's teaching professionalism, school organizational commitment, and school
organizational effectiveness. For the research, I distributed 1,300 questionnaires to elementary
school teachers in 102 schools in Incheon and Gyonggi-do regions and collected back 1,186
copies. Of collected copies, except for 125 copies of missing rainfall data or insincere responses,
I used 1061 copies for research analysis. The results of the study through the process are as
follows: First, the result of analysis on effects school principal's instructional leadership's
sub-variables on teacher's teaching professionalism, educational goal, curriculum management,
prompting motives, teaching improvement and educational supports have significant effects on
teacher's teaching professionalism. Second, for effects on teacher's school organizational
commitment by school principal's instructional leadership, educational goal, curriculum
management, prompting motives, teaching improvement and educational support have
significant influences on it and as recognition on principal's instructional leadership is higher,
those on teacher's school organizational commitment become higher. Third, for effects on school
organizational effectiveness by teacher's teaching professionalism, teaching contents, teaching
strategies and teaching management have effects on it. Fourth, according to the direct or
indirect effectiveness analysis of principal's instructive leadership, teacher's teaching
professionalism, school organizational commitment and school organizational effectiveness, it is
significant that principal's instructional leadership have comprehensive, direct and indirect
effects on school organizational effectiveness via teacher's teaching professionalism. Also, for
effects on school organizational effectiveness via school organizational commitment by
principal's instructional leadership, all of comprehensive, direct and indirect effects are
significant. As it show that school principal's instructional leadership's effects on school
organizational effectiveness via teacher's teaching professionalism and school organizational
commitment is bigger than school principal's instructional leadership's direct effects on school
organizational effectiveness, I could confirm that variables of teacher's teaching professionalism
and school organizational commitment are crucial parameter variables explaining school
organizational effectiveness. Through this, in order to raise school organizational effectiveness
by principal's instructional leadership, it implies that it is necessary to recognize importance of
teacher's teaching professionalism and school organizational commitment as parameter.