In this study, we report an oral drug delivery system without any additional process using pH-sensitive biopolymer, alginate, and alginate oligosaccharide with lysozyme as a model drug. These biopolymers exhibited pH-sensitive characteristics such as shrinking at acidic pH and eroding with dissolution at alkaline pH. The incorporation of lysozyme and biopolymers was performed an artificial intestinal juice (pH 6.8). The immobilization efficiency and lysozyme stability in gastric juice (pH 1.2) has been tested by E coil antimicrobial activity. The lysozyme without biopolymer immobilization lost approximately 80-90% of antimicrobial activity than that of pure lysozyme. However, the pH-sensitive biopolymer-controlled lysozyme maintained similar antimicrobial activity compared to that of pure lysozyme (50-90% of cell mortality). Therefore, this simple, easy, and rapid system can be effectively and practically applied for pathogen treatment for in vivo oral drug delivery.