To provide an easy C-terminal peptide enrichment method being applicable for a lot of protein and not requiring C-terminal modification or N-terminal modification of protein.

A method for enriching C-terminal peptide of protein has the steps of: subjecting protein to digestion using an endoproteinase having C-terminal capability of cutting an arginine residue to obtain a digested substance comprising a C-terminal peptide fragment and another peptide fragment; and subjecting the digested substance to contact with a solid-phase carrier having binding capability to arginine and capturing the other peptide fragment with the solid-phase carrier to separate the C-terminal peptide fragment.