Provided are a composition for improving the brain function, which can be orally taken at a low dose, and a method therefor. The composition for improving the brain function contains, as the active ingredient, X-Pro-Pro-Leu-Thr-Gln-Thr-Pro-Val-Val-Val-Pro-Pro-Phe-Leu-Gln-Pro-Glu-Y (wherein X is nil or represents Ile or Asn-Ile and Y is nil or represents Val-Met), X-Val-Val-Val-Pro-Pro-Phe-Leu-Gln-Pro-Glu-Y (wherein X is abscent or represents Thr-Gln-Thr-Pro, Pro-Leu-Thr-Gln-Thr-Pro, Leu-Thr-Gln-Thr-Pro or Pro and Y is abscent or represents Val-Met), or a salt of the same. The method for improving the brain function comprises administering said peptide or a salt of the same.
