To provide a nucleic-acid-containing, soy-sauce-like flavoring that contains a high concentration of nucleic acids that are only 5'-nucleotides derived from fermentation, without adding 5'-nucleotides from outside, and also provide a production method therefor. Said problem is solved by this production method for a fermented flavoring, said method comprising: a step in which a grain feedstock having soybeans, wheat or the like as the main feedstock thereof is inoculated with a koji mold to prepare solid koji, water or salt water is added thereto, and the resulting moromi having a salt concentration of 4% (w/v) or less is heated and broken down； a step in which the moromi is heat-treated and phosphatase is deactivated so as to prepare sterilized moromi； a step in which the sterilized moromi is inoculated with nucleic-acid-producing microorganisms, and nucleic acid fermentation is performed in a container capable of suppressing the inmixing of harmful microorganisms； a step in which the nucleic-acid-producing microorganisms undergo self-digestion and RNA in the microorganisms is released into the moromi so as to prepare an RNA extract； and a step in which nuclease and deaminase act on the RNA extract to convert the RNA extract into flavorful 5'-nucleotides.
