The purpose of this study was to investigate the effect of instructional supervision of microteaching upon teachers\' questioning skill. To achieve this purpose, the following questions were posed. First, what are the effects of the instructional supervision of microteaching upon improving the cognitive level of questioning? Second, what are the effects of the instructional supervision of microteaching upon the degree of variation in the cognitive level of between in teachers\' questions and students\' responses? Third, what are the effects of the instructional supervision of microteaching upon the ratio and cognitive level of students\' responses? The subject for this study were 5 teachers at an elementary school in Pusan city. The experiment period ran for four-weeks. During the first two weeks 5 teachers received a total of six hours of orientation on questioning skill and a mini-course in the supervision of microteaching. This involved defining microteaching and discussing its purpose, procedure and other aspects. The questioning skill techniques which had been explaned theoretically were again discussed with the 5 teachers. The orientation also conversed the format of each microteaching episode for the following two weeks. During the following two weeks the 5 teachers met three times a week for two and half hours for microteaching. The teachers were asked to plan and teach 10 minute lessons to their peers using the questioning techniques. At the end of each lessons, the peers filled out the checklist for 5 minutes. This was immediately followed by a 15～20 minute supervision conference during which the microlesson was critiqued, using the responses filled out on the checklist. The teaching performance of the 5 teachers was recorded in the actual classrooms and observed and analysed before and after the microteaching using the cognitive level analysis interaction model of Minnis & Shrable. The aggregate means of pre-observation and post-observation scores were compared using the t-test of significance. Major findings were as follows. First, as regarding the effects of supervision of microteaching upon improving cognitive level of questioning, it was verified that there was a significant difference between the pre-supervision and post-supervision. Second, as regarding the effects of the supervision of microteaching the upon degree of variation in the cognitive level between the teacher\'s questioning and students\' responses, it was verified that there was a significant difference between the pre-supervision and post-supervision. Third, as regarding the effects of the supervision of microteaching upon the ratio and cognitive level of students\' responses, it was verified thar there was a significant difference between the pre-supervision and post-supervision. In conclusion, the supervision of microteaching caused a significant improvement in the teachers\' questioning skill.