We have recently shown circular polarizers with the homo-structured double-helical metamaterials, which have broader operation bands than those of the single-helical structures [Opt. Lett. 35, 2588 (2010)]. However, trying to get more operation bands deteriorates the extinction ratio. In this paper, we proposed circular polarizers with hetero-structured double-helical metamaterials. The extinction ratios of these circular polarizers are two times higher than those with homo-structured double-helical metamaterials. Furthermore, we qualitatively explained the phenomenon of the higher extinction ratio from the viewpoint of the interaction between the two helix-wires in a double-helical unit.