PROBLEM TO BE SOLVED: To provide a DPP-IV inhibitor which is safe even if used continuously for a long term, is excellent in absorbability from a small intestine, has a strong DPP-IV inhibitory effect, and is excellent in stability in a blood, and to provide a method of the production thereof.SOLUTION: The dipeptidyl peptidase-IV inhibitor contains a peptide obtained by the hydrolysis of a protein from rice bran or unpolished rice as an active constituent. Moreover, the production method of the dipeptidyl peptidase-IV inhibitor includes decomposing the protein from rice bran or unpolished rice, extracted from the rice or unpolished rice using an alkaline solution, using a protease from Aspergillus oryzae.
