This paper considers the essence of prejudice, which is the basis of normative grounding as a criterion of cognition and practical action. In the modern era, understanding the concept of prejudice as a criterion for cognition and practical action can be perceived as binary opposition according to the position of both the Enlightenment and hermeneutics. However, this paper does not analyze the confrontational difference between the two epistemological perspectives by treating prejudice as previous studies do; rather, it presents a new epistemological frame of reference. This paper identifies the standard of cognition that defines and grounds human consciousness and prejudice as a criterion of cognition and practical action, which is the normative basis of practical behavior, focusing on two types: prejudice of being and prejudice of becoming. The prejudice of being focuses on identity and presupposes that humans and communities have certain normative values inherent and endowed a priori. To realize the normative value inherent in a priori, the prejudice of being emphasizes the ability of reason. The prejudice of being has universal properties as a fixed value and criterion for judgment. Based on immobility, the prejudice of being insists on a system of existing familiar prejudices and tries to settle in a closed space. Therefore, the prejudice of being emphasizes the reality of the familiarity. On the other hand, the prejudice of becoming considers the difference and gives the meaning of social diversity to human cognition. The prejudice of becoming understands the causality of the phenomenon in which human cognition expands as a relativistic attribute. As the prejudice of becoming emphasizes human intuition for grasping social relationships, it tends to be open, dynamic, and intuitively motivating to seek and transform the frame of cognition hardened by the prejudice of being. In summary, whereas the prejudice of being is defined as the reality of the familiarity that seeks stability, the prejudice of becoming is understood as the possibility of the unfamiliarity that accommodates change.