Taekwondo defined as a martial art is different from Taekwondo as a sport, and so there are many ways to distinguish the sport aspects of Taekwondo from its martial art aspects. In this paper, I offer a theoretical framework with which we can characterize the martial aspects of Taekwondo in the master-disciple relationship as being founded in the concept of "I" and "Thou." Research has shown that in order for Taekwondo players to attain the requisite skills to become an expert in combat techniques, it is necessary to engage in physical training. That training requires that there are, on the one hand, some individuals, who want to learn self-defense skills, and, on the other hand, others who are able to teach these skills. In the area of sports, the former are trainees and the latter are trainers. Thus, just like in any other sport, the training of sport Taekwondo includes a trainer-trainee relationship. However, the training of Taekwondo as a martial art includes the master-disciple relationship. I assert these two relationships are essentially different from each other. I characterize the master-disciple relationship as the "I" and "Thou" relationship, and demonstrate in this paper that it is not reduced to the "I" and "It" relation between a trainer and trainee. Whereas the "I-Thou" relationship is grounded in practical knowledge, the "I-It" relationship is based on technical knowledge. Describing how the "I" and "Thou" relationship is founded in practical knowledge, I want to shed light on the distinctive features of the master-disciple relationship in Taekwondo training.