In this study, the high isoflavone-enriched soy leaves (IESLs) were manufactured by treating with the chemical inducer ethephon, a plant growth regulator, to confirm changes in the properties of soy leaves (SLs), which are underutilized. Ethephon treatment concentrations consisted of 0 (SL1), 150 (SL2), and 300 (SL3) μg/mL. The composition analysis and physiological activity were conducted according to the ethephon treatment concentration of SLs. There was no significant difference in the proximate composition and fatty acids, except for an increase with increasing ethephon treatment concentrations. Depending on the ethephon treatment concentration, free amino acids increased to 1413.0, 1569.8, and 2100.4 mg/100 g, and water-soluble vitamins increased to 246.7, 244.7, and 501.6 mg/100 g. In particular, the functional substance isoflavone increased significantly to 1430.11, 7806.42, and 14,968.00 μg/g. Through this study, it was confirmed that the nutritional components and isoflavones of SLs increased according to the ethephon treatment concentration, a chemical inducer treatment agent. This can be used as a high-value-added biosubstance for raw materials for functional foods, cosmetics, and for natural drugs.
