PROBLEM TO BE SOLVED: To provide a flavor balance adjustment method of a liquid food and drink, capable of improving favorable flavor which a liquid food and drink has, and decreasing or reducing unfavorable flavor, and a flavor balance adjustment agent of a liquid food and drink.SOLUTION: A flavor balance adjustment method of a liquid food and drink includes bringing hydrogen-containing gas into contact with a liquid food and drink raw material. A flavor balance adjustment agent of a liquid food and drink includes hydrogen-containing gas as the active ingredient. The flavor balance adjustment is preferably one or at least two selected from the group consisting of sweetness improvement, Umami improvement, saltiness improvement, sharpness improvement, flavor improvement, mellowness improvement of carbonic acid stimulation, bitterness reduction, astringency reduction, miscellaneous taste reduction, acid taste reduction, livestock meat odor reduction, heat smell reduction, and plant-derived unpleasant odor reduc
