[Problem] Disclosed is an antibody that exhibits excellent cytotoxicity and cell growth inhibition and that is based on an anti-human epithelial cell growth factor receptor (1) (Her1) antibody (528). Further disclosed is a method for producing same, and the like. [Solution] The mutant of an H chain humanized variable region (5H) or an L chain humanized variable region (5L) of the anti-human epithelial cell growth factor receptor (1) (Her1) antibody (528) is the aforementioned antibody characterized by having one to a plurality (for example: 1 to 5, or 1 to 3) of amino acid mutations within CDR2. Further disclosed are antibody molecules containing said region, a nucleic acid molecule coding for these polypeptides, a method for producing said antibody molecules, and the like.
