Helicobacter pylori (H.p.) bacteria are the major causes of gastro-duodenal disease, and some association with stomach cancer has been suggested. Recently, H.p. eradicating treatment has been practiced using antibiotics and proton-pump inhibitors. However, at the same time, some reports have been made on the sideeffects of this treatment ; allergic reactions and uneffective resistant bacteria. Under these circumstances, there is a strong need for medicines, which are less harmful to the body, can be administered repeatedly, are less expensive, and yet as effective as antibiotics in inhibiting the bacteria, and in fact, some studies have been undertaken in this regard. We placed our focus on Bainiku-ekisu (Concentrate of Japanese apricot juice) which, as a Japanese folk remedy, has been used for the treatment of gastritis and enteritis since ancient times, and studied its bacteriosterile affects. The major ingredients of Bainiku-ekisu are citric acid (32%) and malic acid (11%), while its pH represents strong acid. We measured the bacteriosterile effects of Bainiku-ekisu by culturing ten H.p. strains originatig from gastro mucous membrane respectively in a Bainiku-ekisu concentration of 0.156%, 0.313%, 0.625% and 0.9%, and measured the level of MIC (minimum inhibiting concentration of development). As a result, out of ten H.p. strains four of them presented strong bacteriosterile effects in a concentration of less than 0.156%, and six of them, in a concentration of less than 0.313%. Furthermore, in order to measure the bacteriosterile effects against H.p. in the stomach we measured the quantity of bacteria in 0 minutes, five minutes, and ten minutes after mixing ten H.p. strasins suspended in physiological salt solution with a Bainiku-ekisu solution of 0.3% and 0.9% dissolved in aseptic physiological salt solution. As a result, within five minutes after mixing, every one of the ten H.p. strains was observed to present strong bacteriosterile effects. These results suggest that Bainiku-ekisu can be considered as a fool likely to prevent the development of H.p. as well as the future possibility of making clinical applications to H.p. infection.