PROBLEM TO BE SOLVED: To provide an anti-Helicobacter pylori agent that shows antibacterial action selectively on Helicobacter pylori.SOLUTION: The present invention relates to an indene compound such as (1R,3aR,7aR)-7a-methyl-1-((R)-6-methylheptane-2-yl) hexahydro-1H-indene-4(2H)-one represented by the formula or a pharmacologically acceptable salt thereof and an anti-Helicobacter pylori agent comprising the same.SELECTED DRAWING: Figure 1