Antioxidant and anti-diabetic activities of acorn were evaluated by its potential for scavenging stable DPPH free radical, inhibition of lipid peroxidation, reducing power, and inhibiton of ${alpha}-glucosidase;and;{alpha}-amylase$. The water extract of acorn exhibited strong antioxidant and antidiabetic related activities in the tested model systems. Solvent fractionation of the water extract revealed that the water fraction and the EtOAc fraction had strong antioxidant activity, and inhibitory activity on ${alpha}-glucosidase;and;{alpha}-amylase$. The water fraction exhibited higher DPPH radical scavenging activity ($EC_{50}=7.19{mu}g/mL$) than that of ${alpha}-tocopherol;(EC_{50}=7.59{mu}g/mL)$. It is considered that water extract of acorn has the potential for natural antioxidant and anti-diabetic products.