The purpose of this study was to explore the professional development of elementary school English teachers by focusing on the process of gradual change in teachers’ beliefs and the way of teaching English phonetic and phonological features. This study discussed the case of a teacher who had high English proficiency and was in the early stages of her career in elementary school. The author observed her lessons, had semi-structured interviews, called ‘reflection’, after lessons, and analysed these narrative data over four years. At first, the teacher believed that the ALT, a native English speaker, was the ideal model for pronunciation and that it was essential for her students to listen to and imitate the ALT’s pronunciation as frequently as possible. However, after the second year, since she began to teach with non-native English-speaking ALTs, she often faced a conflict between the varieties of English and the English-like pronunciation. It was also indicated that this conflict was affected by the multiple I-positions she had as a second-language speaker of English, an English teacher, and a part-time teacher, and other roles.