NOVELTY - Dried grapefruit is crushed, added to hot water, heated, extracted and filtered, to obtain filtered liquid. The total filtrate is concentrated, crystallized, saturated and filtered, to obtain crystals. The crystals are washed with pure water, hydrolyzed with hydrochloric acid aqueous solution, rapidly cooled, crystallized, suction-filtered and dried, to obtain crude crystals of naringenin. Ethanol is added to crude crystals of naringenin and heated. The crystals of naringenin are completely-filtered, and the filtered cake is washed and vacuum-dried, to obtain naringenin.    USE - Extraction of naringenin from grapefruit (claimed).    ADVANTAGE - The method enables economical and environmentally-friendly extraction of naringenin with high yield, high extraction rate and reduced usage of organic solvent, within short period of time by simple method, without using column.    DETAILED DESCRIPTION - Dried grapefruit is crushed, and sieved for 10 meshes or more, to obtain sieve material. The sieve material is provided into hot water at 80-90 degrees C, heated at 95 degrees C or more for 1-2 hours, extracted and filtered. The filtered liquid is added to hot water at 80-90 degrees C, heated at 95 degrees C or more for 1-2 hours, extracted and filtered, to obtain filtered liquid. The total filtrate is passed through horizontal screw machine and horizontal-spiral centrifuge rotated at speed of 12000 rpm, and impurities are removed mechanically. The total filtrate is cooled to 60 degrees C or less, separated and purified using an ultrafiltration membrane to remove filtrate macromolecular substances. The liquid concentrate is passed through a membrane, and processed at pressure of 0.45-0.9 MPa. The liquid is provided to decompression concentration tank, and the extract is concentrated. The concentrated extract is provided to clean crystal inner container, crystallized, cooled at 1-2 degrees C, saturated and filtered, to obtain crystals. The crystals are washed with pure water having content of 2 times or more with respect to crystals, and crystals are dried, to obtain product (p1). The product (p1) is hydrolyzed with hydrochloric acid aqueous solution having concentration of 1.5 mol/L, rapidly cooled at 25-28 degrees C, crystallized for 10 hours, and the crude crystals are suction-filtered, collected, separated and dried, to obtain crude crystals of naringenin. 60-85 %mass Ethanol is added to crude crystals of naringenin, heated at 80 degrees C such that crude crystals of naringenin are completely dissolved and cooled to 2-3 degrees C. The crystals of naringenin are completely-filtered, and the filtered cake is washed with purified water for two times and vacuum-dried at 80 degrees C, to obtain naringenin.