This study empirically investigated whether the levels of student’s satisfaction and credibility on an English teacher are high under the high degree of contextual fitness in the transformational leadership of an English teacher. The contextual variable in this study includes the English self-efficacy of a student. For this study, a questionnaire survey was performed. Participants were both first and second grade high school students in seven districts of Daegu, Korea. From the survey, 219 questionnaires were collected. Cluster Analysis was employed to analyze the levels of fitness between students’ English self-efficacy and the transformational leadership of an English teacher. The result showed that when the degrees of English self-efficacy are high, if the dimensions (i.e., consideration and influence, inspirational motivation, intellectual stimulation) of transformational leadership is highly actualized and the levels of intellectual stimulation are higher than consideration and influence, inspirational motivation, then, the levels of the students’ satisfaction and credibility about the English teacher are high. It was also found that when the levels of English self-efficacy are low, if the realizations of consideration and influence, inspirational motivation are higher than that of intellectual stimulation, then, the degrees of the students’ satisfaction and credibility was relatively high.