A nitridosilicate-based compound is produced by reacting an alkaline-earth metal compound capable of generating an alkaline-earth metal oxide by heating or a rare earth compound capable of generating a rare earth oxide by heating with at least a silicon compound, while the alkaline-earth metal compound or the rare earth compound is being reduced and nitrided by the reaction with carbon in an atmosphere of nitriding gas. Because of this, a nitridosilicate-based compound of high quality can be produced industrially at low cost.