We previously reported various solid solution systems that demonstrated the stabilized antiferroelectric (P) phases in NaNbO 3 through lowering the tolerance factor. However, all those reported modifications were achieved by adding A 2+ B 4+ O 3 type solid solutions. A lead-free antiferroelectric (AFE) solid solution xBiScO 3 -(1-x)NaNbO 3 was rationalized by adopting the tolerance factor design rule. Specifically, adding BiScO 3 was found to effectively stabilize the AFE phase without changing the crystal symmetry of NaNbO 3 . Microstructure and electron zone axis diffraction patterns from transmission electron microscopy revealed the stabilized AFE (P) phase in this solid solution. Besides, the electric-field-induced polarization with a double-hysteresis loop was observed. The present results pointed out that the strategy could also be applied while adding A 3+ B 3+ O 3 type solid solutions. In addition, it expanded the compositional design that can be applied to antiferroelectric materials.