It is undeniable that teachers play the principal roles in education. This is why education and professional development of teachers are so important. Some of recent works have made this fact clearer. In America, in particular, many reports and research papers have recently been published on these problems. In this paper, we first introduce briefly the current system of education, employment, and professional development of mathematics teachers in Korea. And then we mention a research project on education of mathematics teachers. The final report of the project contains some suggestions for curriculums of the department for education of mathematics teachers. We describe one example of extended syllabus which implements those suggestions. The example is on Modern Algebra I.