The method for producing a perovskite metal oxynitride of the present invention, comprises: a hydrogenation step (A) of forming a perovskite oxyhydride in which an oxide ion (O2−) and a hydride ion (H−) coexist, by reducing a perovskite oxide through a reductive oxygen elimination reaction using a metal hydride; and a nitriding step (B) of forming a perovskite oxynitride containing a nitride ion (N3−) by heat-treating the perovskite oxyhydride in the presence of a nitrogen source substance at a temperature of 300° C. or higher and 600° C. or lower and exchanging the hydride ion (H−) for a nitride ion (N3−).