The present invention relates to a type 2 helper T cell-selective immune response inhibitor, an immune response regulator and an anti-allergic agent, individually comprising, as an active ingredient, a purine derivative represented by General Formula (I): wherein R2 is hydrogen or a hydrocarbon group in which —CH2— not directly bound to the purine skeleton may be substituted by CO, SO2, O or S, and C—H not directly bound to the purine skeleton may be substituted by N, C-halogen or C—CN; R6 is hydroxyl, amino or amino which is mono- or di-substituted by a hydrocarbon group(s); R8 is hydroxyl, mercapto, acyloxy or hydrocarbon group-substituting oxycarbonyloxy; and R9 is a hydrocarbon group in which —CH2— not directly bound to the purine skeleton may be substituted by CO, SO2, O or S, and C—H not directly bound to the purine skeleton may be substituted by N, C-halogen or C—CN; or its tautomer or a salt of the purine derivative or the tautomer.