Provided are a novel collagen peptide composition production method, as well as a DPP-4 inhibitor and an antihyperglycemic agent containing said collagen peptide composition. This peptide composition including a peptide represented by X-Hyp-Gly (where, X is an amino acid residue other than Gly, Hyp, and Pro) is generated by adding and dissolving ginger rhizome-derived enzymes in a collagen and/or gelatin solution. The collagen peptide composition thus obtained exhibits high DPP-4 inhibitory activity, and an excellent antihyperglycemic effect.