PROBLEM TO BE SOLVED: To provide an anti-Helicobacter heilmannii agent which has an intragastric microorganism number-reducing action or eradication action against Helicobacter heilmannii which has become clear that it is involved in development of gastritis, gastric ulcer, mucosa-associated lymphoid tissue (MALT), and the like, in intragastric infection to including a human, canine, feline, swine, monkey, and the like.SOLUTION: The invention provides an anti-Helicobacter heilmannii agent which contains as an active ingredient lactic acid bacteria and/or lactic acid bacteria culture belonging to Lactobacillus.