Disclosed is a disinfectant which is safe, has few adverse side-effects, can be ingested together with a food or beverage by adding the disinfectant to the food or beverage, shows a bactericidal effect in the oral cavity, and has no problem even when ingested on a daily basis over a long period. Also disclosed is a food additive comprising the disinfectant. Specifically, disclosed is an oral disinfectant for the disinfection of an oral bacterium, which comprises lactoperoxidase, glucose oxidase, glucose and a pH-adjusting component.
