Abstract: The present invention provides for a method for improving properties of an antibody such as an expression level and stability. A method for obtaining an antibody with an improved expression level and/or stability by modifying a human antibody or a humanized antibody, characterized by that at least any one of the amino acid residues at position 8, 12, 15 or 18 (according to Kabat numbering) in a light chain variable region (hereinafter referred to as “VL chain”) of a human antibody or a humanized antibody is substituted with a different amino acid other than proline or cysteine, and a human antibody or a humanized antibody or a human antibody fragment or a humanized antibody fragment with an improved expression level and/or stability which are obtained by said method.