Abstract: This invention relates to an adenine derivative, a tautomer thereof, or a pharmaceutically acceptable salt thereof represented by general formula (I): wherein X represents NR3 (wherein R3 represents a hydrogen atom or C1-3 alkyl) or the like; R1 represents substituted or unsubstituted alkyl or the like; R2 represents hydroxyl or the like; and Y represents a substituted or unsubstituted aromatic hetero ring or the like. Also, the present invention relates to pharmaceuticals such as an interferon inducer, antiviral agent, anticancer agent, type 2 helper T cell selective immune response inhibitor, antiallergic agent, and immune response modulator comprising the above derivative as an active ingredient.