Tonin(Persicae Semen) is the herb medicine that contains amygdalin as a major ingredient. Amygdalin in water is decomposed into benzaldehyde, HCN, and glucose by emulsin, a hydrolysis enzyme in tonin. A useful and practical method for the optimum extraction condition of amygdalin without enzymatic hydrolysis is required. The extraction yield of amygdalin of natural formula to nin was 0.1 % from crude powders, 1.4% from small pieces, 3.5% from half pieces and 2.4% from whole pieces. The extraction yield of amygdalin of outer shell-eliminated to nin was 0.3% from crude powders, 1.4% from small pieces, and 3.5% from half pieces and whole pieces respectively. The extraction yield of amygdalin was most high when using the size larger than half.