The present invention relates to a method for economically preparing ginseng extract having an increased content of physiologically active substances, comprising the steps of steaming ginseng at 95 to 100.degree. C. for 1 to 24 hours, collecting the generated vapor by cooling, and repeating the process twice, to a composition for promoting collagen synthesis, comprising the extract, and to a cosmetic product for improving skin wrinkles, comprising the composition.