The main objective of this study was to investigate whether orally administered Korean grain larvae ethanol extract (GLE) has a bifidogenic effect in normal rats. Male Sprague Dawley rats were divided into a negative control group (CO) and GLE orally administered (5.0, 7.0, and 9.0 mg/100 g body weight) groups. Thymus and spleen weights dose-dependently increased by 128.58% and 128.58%, respectively, but abdominal fat decreased by 19.18% after GLE administration compared with that in the CO group (p < 0.05). Serum triglycerides, total cholesterol, low-density lipoprotein cholesterol, and glucose decreased by 30.26, 7.33, 27.20, and 6.96%, respectively, whereas high-density lipoprotein cholesterol increased by 129.93% in the GLE groups compared with those in the CO group (p < 0.05). IgG, IgM, IgA in the GLE groups increased 203.68%, 181.41%, and 238.25%, respectively, compared to that in the CO group (p < 0.05). Bifidobacteria and Lactobacillus increased by 115.74% and 144.28%, whereas Bacteroides, Clostridium, Escherichia, and Streptococcus decreased by 17.37, 17.46, 21.25, and 19.16%, respectively,in the GLE groups compared with those in the CO group (p < 0.05). Total organic acids, acetic acid, and propionic acid increased by 151.40, 188.09, and 150.17%, whereas butyric acid and valeric acid decreased by 40.65 and 49.24%, respectively, in the GLE groups as compared with those in the CO group (p < 0.05). These results suggest that Korean GLE improves the bifidogenic effect by increaseing cecal organic acids and modulating gut microflora via a selective increase in Bifidobacterium in normal rats.