The purpose of this study is to analyze the gap of the pedagogical content knowledge among the elemenraty school teachers on instructing students in game activity. We divided the teachers into four groups; who has an abundant career and specialized in physical educaion at graduate school, who has an abundant career but not specialized in physical education at graduate school, who has a little teaching career but specialized in physical education at graduate school, who has a little teaching career and not sperialized in physical education at greduated school. And I restricted the study to only game activity. I applied a case study and collected lots of materials from various techniques which are depth interview, photographing literatures research, etc. I analyzed the collected materals with inductice logic and testified the truth of the matericals with personel organization examination, colleague discussion and multivariate abalysis. And I got the following results. 1. In the comprehension of curriculum : The specialized teachers think it as a variable thing by the social demand the circumstance of school or students. So they think it very importantly. 2. In the line of instruction content: The teacher whol has an abundant career and sperialized in physical education at graduate school thinks physical education must be done synthetic method of cognition, emotion and purpose. This fact indicates that a successful instruction need a good teacher who has a career and an special pedagogical content knowledge. 3. In the value system: The teachers who specialized in physical education evaluate not only the development of an athletic ability but also emotional- purposive area. But the newly appointed teacher who did not specialize in physical education at greduated school focused only the emotional side. Lately most of specialist encourage the joyful athlete. At that point, his value system can be good one. but he has neither objevtivity nor consistency of his evaluation behaviors. 4. In the comprehension of student character: At individual difference, the teacher who has an abundant career and specialized in physical education at graduated school comprehended the students by various points(Physical and emotional points). But the teacher who has an abundant career but not specialized in physical education at graduate school comprehended the students\' emotional side.