A novel lactic acid bacterium strain is found, which has a high IgA production-inducing ability and a high immunostimulating activity, and belongs to the genus Enterococcus. Thus, provided is an excellent lactic acid bacterium preparation for foods or feeds, which has a high enteric colonization rate. Specifically disclosed are: a novel lactic acid bacterium Enterococcus faecium NHRD IHARA (FERM BP-11090) which has a high IgA production-inducing ability and a high immunostimulating activity； and a lactic acid bacterium preparation for enhancing the production of immunoglobulin A, which comprises a culture of the bacterium strain, an extract of the bacterium strain, or a product of any treatment of cells of the bacterium strain.
