This study investigated the antimicrobial activity of soy protein isolate (SPI) film containing green tea extract (GTE, 1-4%, w/w) on dental caries-inducing bacterium (Streptococcus mutans), food pathogenic (Staphylococcus aureus, Escherichia coli 0157, Salmonella typhimurium), and spoilage (Pseudomonas aeruginosa) bacteria. The physical and mechanical properties of the SPI film containing GTE were also studied. The SPI film containing GTE (4%, w/w) exhibited good antimicrobial activity against S. mutans and S. aureus. The antimicrobial activity of the SPI film containing GTE increased against S. mutans as the concentration of GTE increased up to 4%(w/w). SPI films containing GTE showed lower tensile strength and elongation, and higher total soluble matter than those of control SPI film. Therefore, GTE can be used as one of antimicrobial agents for anti-dental caries and food packaging films.