Abstract: It is intended to provide antibodies, in particular, monoclonal antibodies against, as antigens, peptides comprising N-terminal ? amino acid sequences of a protein CENP-A expressed in centromeres in chromosome and a process for producing the same. Antibodies against partial-length peptides of the CENP-A protein expressed in centromeres in chromosome (preferably a peptide having the amino acid sequence of 3- to 19-positions of the CENP-A protein, a peptide having the amino acid sequence of 27- to 40-positions thereof or a peptide having the amino acid sequence of 126- to 140-positions thereof); and a process for producing the same. A method of solubilizing a centromere chromatin while sustaining its completeness by treating with 0.3 M NaCl and MNase. A method of using an anti-CENP-A antibody which comprises chemically bonding the antibody to a support and isolating and purifying the same by the immunoprecipitation method.