An interposer includes: a base substrate; an interconnection structure on a top surface of the base substrate and including a metal interconnection pattern; an upper passivation layer on the interconnection structure and having compressive stress; a lower passivation layer under a bottom surface of base substrate, the lower passivation layer having compressive stress that is less than the compressive stress of the upper passivation layer; a lower conductive layer under the lower passivation layer; and a through electrode penetrating the base substrate and the lower passivation layer. The through electrode electrically connects the lower conductive layer to the metal interconnection pattern of the interconnection structure.