It is intended to provide a composition containing isoflavones which has a high purity and yet is highly soluble in water in a natural state without adding any solubilizers or subjecting to chemically modification. It is found out that a composition containing isoflavones with a high purity and a high solubility in water can be obtained by extracting soybean hypocotyls with a water-containing alcohol within a specific temperature range, then allowing a synthetic adsorbent resin to adsorb the obtained extract and eluting with a water-containing alcohol at a specific concentration.