To obtain a flame retardant nonwoven fabric thinner than conventional ones and having heat resistance, chemical resistance, electrical insulating property, corrosion resistance and high purity, thus useful in the field of ceramic industry, etc., by entangling incombustible or flame-retardant fiber with a substrate.

This method for producing a flame-retardant nonwoven fabric comprises entangling incombustible or flame retardant short ceramic fiber 2, etc., with a cloth made of gauze substrate 1, etc., prepared by ordinary method in advance. It is preferable to make the incombustible or flame-retardant fiber easily tangle with the substrate 1 by infiltrating an infiltrative substance into the substrate 1 and loosening its fibrous structure.