The present invention is to obtain a novel gene that encodes a protein having a function of promoting acetic acid bacterial growth in the presence of a high concentration of acetic acid; to enhance acetic acid bacteria's function of promoting growth and thereby to develop acetic acid bacteria with an improved fermentation ability in the presence of a high concentration of acetic acid; and to provide a method for efficiently producing vinegar that contains a high concentration of acetic acid in a short time using the acetic acid bacterium. A novel gene having a function of improving the function of promoting growth at a practical level was cloned from acetic acid bacteria for practical use, belonging to the genus Gluconacetobacter, by a method comprising exposing acetic acid bacterial lysate to the presence of a high concentration of acetic acid; obtaining a gene of a protein that was not insolubilized but remained soluble; and thereby obtaining a gene having a function of promoting acetic acid bacterial growth in the presence of acetic acid. When cultured in the presence of acetic acid and ethanol, a transformant of acetic acid bacteria transformed with the gene was confirmed to have a significant effect of promoting growth.