Various mushroom extracts were examined for their anti-Streptococcus mutans and anti-glucosyltransferase (GTase) activities. Mushrooms were extracted with chloroform, methanol, acetone, ethyl acetate, and distilled water. The chloroform, methanol, and ethyl acetate extracts showed higher antimicrobial activity than that of the others. The inhibitory effects of the chloroform, methanol, and ethyl acetate extracts of Lyopyllum ulmarium, which have high anti-microbial and GTase activities, on the growth of S. mutans were examined and the optimal ratio of solvents was also evaluated to investigate the influence of solvents using a simplex centroid design. The anti-cariogenic effects of the L. ulmarium extract on S. mutans was influenced by the solvent, and the optimum anti-cariogenic activity of the extract was obtained with the ratio of chloroform:methanol:ethyl acetate=1:1:1 (v/v/v). These results suggest that solvent selection is an important factor to extract anti-cariogenic materials effectively from mushrooms.