The inhibitory activities of a water extract of Sanghwang mushroom(Phellinus linteusau)(SWE) against ${alpha}$-glucosidases were evaluated in this study. Inhibiting these enzymes involved in the absorption of disaccharides significantly decreases the postprandial increase in blood glucose level after a mixed carbohydrate diet. Oxygen radical absorbance capacity and 1,1-diphenyl-2-picryl hydrazyl scavenging activities of the SWE were evaluated to investigate the antioxidant activity of the SWE associated with complications of long-term diabetes. Furthermore, the postprandial blood glucose lowering effect of SWE was compared to a known type 2 diabetes drug($Acarbose^{(R)}$) in a Sprague-Dawley rat model. SWE significantly reduced the blood glucose increase after sucrose loading. These results suggest that SWE, which has high ${alpha}$-glucosidase inhibitory activity and high antioxidant activities, has the potential to contribute to a useful dietary strategy for controlling postprandial hyperglycemia.