The growth of Bifidobacterium and Lactobacillus isolated from human interstinal bacteria were induced by water extract and II-step extract of soybean and carrot and the pH of these bacteria-cultured media were decreased. The increasing growth rates of these bacteria are related to the decrease of the pH of these bacteria-cultured media. When human intestinal flors as starter were inoculated into the medium containing water extract of soybean and carrot, the growth of lactic bacteria were also induced and the pH of the media were decreased. By measuring the pH of the media which were inoculated and cultured intestinal bacteria as a starter, it is possible to determine whether the food are die growth factors of intestinal lactic add bacberia or not. By this method, the food which decreased pH of the medium were soybean, turnip, carrot, leek, garlic, dropwork, wormwood and onion. These foods may induce lactic add bacteria in human intestine.