Disclosed are: a compound which is stable in an acid, has an antibacterial effect against a bacterium Helicobacter pylori, can exert a satisfactory level of an antibacterial effect when used singly, does not affect an enteric bacterium, has an antibacterial effect against a bacterium resistant to an antibacterial agent, and has an inhibitory effect on gastric acid secretion； and a pharmaceutical composition comprising the compound. Specifically disclosed are: a compound represented by the general formula (I) or a salt thereof； and a pharmaceutical composition comprising the compound or the salt thereof:wherein R represents a linear alkyl group having 4 to 8 carbon atoms, preferably 5 to 7 carbon atoms.
