Atomic substitutions in newly developed ThMn12-structure magnet materials. Substitution of Ti for Fe(8i) site and Zr for R(2a) site are confirmed by Cs-STEM. Amount of precipitated α-(Fe,Co) phase increased with Tix decreasing (x = 1.0 → 0.5). Zr substitution for R(2a) sites stabilized ThMn12 structure in Ti-poor phase. Tix (x = 0.5–0.75) and Zry (y = 0.1–0.3) is optimum composition for properties.