Chimeric alpha-amylase, produced by recombinant yeast cells, was purified by immunoaffinity chromatography by use of an anti-peptide antibody and an eluent containing an antigen peptide. Chimeric alpha-amylase was adsorbed by the antibody against the peptide corresponding to the C-terminal region of target alpha-amylase, and specifically eluted by the eluent containing the antigen peptide used for immunization. A low concentration of the peptide could competitively elute adsorbed alpha-amylase, and the rate-limiting step of the elution was mass transfer of desorbed alpha-amylase. With this specific method, target proteins can be effectively eluted, and highly purified under mild conditions, from the antibody ligand showing a high-affinity for the adsorption step.