Abstract: An immunoglobulin-binding protein has an improved chemical stability, especially having an improved alkaline stability, or an immunoglobulin-binding protein capable of allowing antibody elution under mild pH conditions, and an adsorbent on which the protein is immobilized. The alkaline stability or the antibody elution property is improved by including an amino acid sequence which is the same as an amino acid sequence of an immunoglobulin-binding domain of protein L derived from a bacterium belonging to the genus Finegoldia except that the amino acid residue(s) at a particular position(s) of the domain in the amino acid sequence is/are substituted with another particular amino acid residues(s).