The purpose of this study is to compare between theory of knowledge of constructivism and postmodernism and to discuss education of two theories based on the result. The result of this study insists constructive theory of knowledge to consider characteristics and rigidity of conveying method of objective theory of knowledge as well as situationality and contextualism of knowledge. It also insisted that post modernism theory of knowledge emphasizes the role of language game in knowledge construction and standards of each game holds incommensurability. Therefore, knowledge of which postmodernism seeks is something that recognizes differences among rules of each game and denies foundationalism view of knowledge. Comparison between two theories based on the discussion of theories resulted a discussion about common features and differences. Both theories supported situational and contextual access of knowledge and need of considering social and cultural aspects of utilizing discourses in a macroscopic. However they showed differences in important problems such as “do two theories approve aspects of the traditional education?” or “do they deny the traditional theory itself?” in a microscopic view. Constructivism education can be comprehended as a theory that recognizes significance of traditional education and tries to improve mistaken methodology. On the contrary, postmodern education suggests a new education that completely denies the traditional education. Education philosophical implication of this study is to assist use of definitions and increased accuracy of analyzing meanings for further studies similar to this study by considering macroscopic common features and microscopic differences of two theories suggested above.