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 LLE OR ASN-LLE 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.