The purpose of the present invention is to provide a novel IL-2 variant that has an improved selectivity for IL-2Raß? and selectively activates Treg. The present invention pertains to: an IL-2 variant; a method for producing the IL-2 variant; a composition containing the IL-2 variant; a therapeutic agent for an immunological disease containing the IL-2 variant; a method for elevating the selectivity of IL-2 for IL-2Raß?; a method for improving the affinity of IL-2 for IL-2Ra subunit; a method for lowering the affinity of IL-2 for IL-2Rß and/or ? subunits; and a method for selectively activating a regulatory T cell.