Provided are an intestinal barrier function enhancer capable of enhancing intestinal barrier function and thereby capable of preventing or treating metabolic syndrome, and a drug and a food or drink containing the same. An intestinal barrier function enhancer containing cells or a treated cell product of Lactobacillus crustorum. This intestinal barrier function enhancer functions effectively to enhance intestinal barrier function and to prevent or treat conditions or diseases caused by impaired intestinal barrier function such as metabolic syndrome and the like.
