PROBLEM TO BE SOLVED: To provide a method of producing a lemon juice fermentation liquid which makes it possible to obtain a fermentation liquid having the excellent umami of lemon juice and a new flavor.SOLUTION: A method of producing a lemon juice fermentation liquid includes a fermentation step for fermentation of lemon juice liquid with lactic acid bacterium, wherein the lactic acid concentration of the lemon juice fermentation liquid is 1000 mass ppm or more based on the total amount.