The present invention relates to a synbiotic food composition, which is a food composition for promoting the active intestinal growth of Lactobacillus sp. lactic acid bacterium, containing lactic acid bacteria and tagatose as a source of nutrients for the bacteria strain. More particularly, the present invention relates to a synbiotic food composition containing a Lactobacillus casei strain or Lactobacillus rhamnosus strain as a probiotic, and tagatose as a prebiotic.