Disclosed are a novel pyridine thio derivative, and a pharmaceutical composition using the novel pyridine thio derivative, particularly a pharmaceutical composition having selective antibacterial activity against Helicobacter pylori. Specifically disclosed is a pyridine thio derivative represented by general formula (I) (wherein R1 and R2 each represents a hydrogen atom, a C1-8 alkyl group or the like； R3 and R4 each represents a hydrogen atom, a C1-8 alkyl group or the like； X represents —O—, —S— or the like； Y represents a C1-12 alkyl group which may be substituted by a substituent or —(R5—O)n—R6 (wherein R5 represents a C1-5 alkylene group； R6 represents a C1-8 alkyl group which may be substituted by a substituent, and n represents an integer of 1-10)； and Z represents a hydrogen atom or the like), or a pharmacologically acceptable salt thereof. Also specifically disclosed is a pharmaceutical composition containing the pyridine thio derivative or a salt thereof.
