The purpose of this study is to explore the interrelationships among principals' supervisory actions (hereafter PSB), teachers' beliefs about supervision (hereafter TBS), and the effect of supervision (hereafter SE). In this study, the responses from 1203 teachers(collection rate 96.24%) of 125 elementary schools in Incheon, Seoul, Gyeonggi, Busan, Daegu and Gwangju were analyzed. Correlation analysis and multiple regression analysis were operated to examine the interrelationships of the three factors and their influence on one another. Based on the result of the regression analysis, structural equation modeling was executed to verify the effect of the TBS mediating the PSB and SE. The results of the study are as follows. First, the SE was higher with cooperative and directive PSB. It is suggested for the principals to perform directive and cooperative supervision with close contact with the teachers to be more effective. In a period in which in-school self-regulated supervision is rooting, the result provides a significant suggestion for implementing the types of PSB. Secondly, directive PSB was related to bureaucratic TBS, non-directive PSB democratic TBS. However, cooperative PSB had no meaningful effect on TBS. The PSB types which influenced the TBS and SE were various. It can not be asserted that non-directive PSB are positive and directive PSB negative. Thirdly, it was revealed that the effects of supervision are influenced by both the TBSs. Therefore, it is arguable that the bureaucratic belief is negative and the democratic positive. It is desirable to examine the two beliefs comprehensively as independent aspects rather than in a dichotomous way. Fourthly, The structural modeling verification on the PSB, TBS, and SE revealed that both the non-directive PSA and directive PSA affect the SE directly and indirectly through TBS. It suggests that higher SE can be expected with tailored PSA with stronger influence on the TBS construction