This study aimed to develop a teacher educator training program trying to improve the planning and conducting skills in in-service teacher training. We tested out the teacher educator training program in two graduate-level courses. One of them, “Special Lecture on Teacher Education,” took up the theories relating to human resource development and adult education and knowledge needed for planning and conducting in-service teacher training programs. In another course, “Seminar on Teacher Education,” the students developed and conducted the simulated in-service teacher training program. This study assumed that these two programs of teacher educator training program could contribute to improving the students’ planning and conducting skills in in-service teacher training.