An L-amino acid is produced by culturing a microorganism of the family Enterobacteriaceae which has the ability to produce an L-amino acid and which has been modified so as to increase the expression of the evgA gene, the gadE gene, and/or the ydeO gene. These genes encode a transcription factor involved in the EvgAS two-component system regulon. The culture takes place in a medium, and the L-amino acid is collected from the medium or cells.