PURPOSE: To efficiently improve extraction of component readily absorbable and soluble in organisms by reacting an extracted solution containing a water- soluble component of ginkgo leaf and ginkgo leaf with a partial hydrolyzate of starch and glycosidase, etc.

CONSTITUTION: Ground dried ginkgo leaf is extracted with a water-ethanol mixed solution having ≤80wt.% ethanol at 30-60°C to give a water-soluble component (A) containing flavonoid, etc. Then the component A is blended with 1-100 pts.wt. based on 100 pts.wt. ginkgo leaf in the component A of partial hydrolyzate of starch (e.g. maltose) and glycosidase or transglycosidase and extracted under heating to give an extracted solution (B) wherein components contained in the ginkgo leaf are subjected to saccharide transition. Then the glycoside in the component D is separated, purified and then concentrated to produce glycoside essence of active ingredient of ginkgo leaf.