The present invention relates to a composition for improving intestinal flora and enhancing immune response containing Cinnamomum cassia bark extract as an effective ingredient, more precisely, a composition containing Cinnamomum cassia bark extract is an effective ingredient that has the effects of increasing the growth of such intestinal beneficial bacteria as Bifidobacterium longum, Lactobacillus sp. and Lactobacillus acidophilus and enhancing the proliferation of immune cells such as lymphocytes of general immune system as well as increasing the activity of intestinal immune cells. The composition of the present invention can be effectively used as a therapeutic agent for constipation or other intestine-related diseases and an immune enhancer owing to its activity of increasing immunity, particularly intestinal immunity, by increasing immune cell proliferation.