The present invention provides (1) a method for producing a non-human animal having a humanized liver, comprising transplanting human hepatic stem cells and/or hepatic progenitor cells and/or immature hepatocytes to a liver-damaged non-human animal to induce the differentiation of the cells into hepatocytes, (2) a non-human animal having a humanized liver, produced by the method, (3) a method for examining the pharmacokinetics and/or hepatotoxicity of a test substance, comprising using the animal, (4) a method for producing human hepatocytes, comprising transplanting human hepatic stem cells and/or hepatic progenitor cells and/or immature hepatocytes to a liver-damaged non-human animal to induce the differentiation of the cells into hepatocytes, and (5) a method for examining the pharmacokinetics and/or hepatotoxicity of a test substance, comprising using human hepatocytes produced by the method.
