Study of the NO decomposition activity of the Ruddlesden-Popper-type oxide Sr3Fe2O7 doped with Ba and Zr revealed that Sr3Fe2O7 exhibits a high NO decomposition activity. Doping Ba and Zr for the Sr and Fe sites, respectively, is highly effective for improving NO decomposition activity. A high N-2 yield of 72% is achieved at 1123 K and a N-2 yield of 32% is sustained under a 2.5% oxygen cofeeding condition.