It is necessary to determine the pyruvic acid concentration of the moromi-mash when filtering the moromi-mash, separating sake and cake from the moromi-mash, and when alcohol is added to the moromi-mash fermentation process.We found that a 0.956 correlation coefficient was obtained between the pyruvic acid concentration determined by the standard methods (enzyme reaction methods) and measurment of the optical density of the 3-deoxyglucosone concentration in 61 commercial ginjo sakes.When ginjo-moromi-mash samples were filtered, a correlation coefficient of 0.933 was obtained between the pyruvic acid concentration determined by the standard methods and the measurment of 3-deoxyglucosone concentration.The use of the 3-deoxyglucosone concentration assay makes it easy to determine the pyruvic acid concentration of ginjo sake and ginjo-moromi-mashs.