A method for extracting useful substances from the cell wall of deer horn shaped Ganoderma lucidum is provided to improve extraction yield, rapidness and economical efficiency of useful substances including beta-glucan without damage of them by using hot water. A method for extracting useful substances from the cell wall of deer horn shaped Ganoderma lucidum comprises the steps of: pressurizing the water to a pressure equal to or more than saturated vapor pressure(0.1-5.0 MPa) and heating the water to extraction temperature(145-190°C) to prepare pressurized hot water contacting the pressurized hot water with the deer horn shaped Ganoderma lucidum for 120 minutes to hydrolyze it and extracting useful substances including mainly beta-glucan from the hydrolyzed deer horn shaped Ganoderma lucidum.
