A method for producing a transgenic immunodeficient mouse expressing hIL-6 transgene comprising human liver cells transplanted therein, wherein the immunodeficient mouse expressing hIL-6 transgene that has impaired or lowered immune reactions against humans is induced to have liver injury in the liver and the human liver cells transplanted in the liver of the immunodeficient mouse expressing hIL-6 transgene are allowed to be engrafted therein instead of the liver cells of the immunodeficient mouse expressing hIL-6 transgene and the human liver is reproduced, wherein the reproduced liver has a portal triad composed of the interlobular artery, the interlobular vein, and the interlobular bile duct and functions of the human liver and the liver injury is induced by any of methods (i) to (iv) described below: (i) a method of liver injury induction in the liver of a immunodeficient mouse expressing hIL-6 transgene that has impaired or lowered immune reactions against humans and carries the thymidine kinase gene in an expressible manner by administering human liver cells and suicide substrates to the immunodeficient mouse expressing hIL-6 transgene; (ii) a method of liver injury induction in the liver of a immunodeficient mouse expressing hIL-6 transgene that has impaired or lowered immune reactions against humans by allowing the urokinase-type plasminogen activator gene to be carried in an expressible manner therein; (iii) a method of liver injury induction by impairing the fumarylacetoacetate hydrolase (Fah) gene of the immunodeficient mouse expressing hIL-6 transgene that has impaired or lowered immune reactions against humans; and (iv) a method of liver injury induction by administering any of the compounds (a) to (e) below: (a) carbon tetrachloride; (b) acetaminophen; (c) d-galactosamine; (d) thioacetamide; and (e) anti-Fas antibody; and wherein: the human IL-6 gene is introduced into an immunodeficient mouse and expressed therein to allow human IL-6 to be present in vivo, resulting in the immunodeficient mouse expressing hIL-6 transgene. (i) a method of liver injury induction in the liver of a immunodeficient mouse expressing hIL-6 transgene that has impaired or lowered immune reactions against humans and carries the thymidine kinase gene in an expressible manner by administering human liver cells and suicide substrates to the immunodeficient mouse expressing hIL-6 transgene; (ii) a method of liver injury induction in the liver of a immunodeficient mouse expressing hIL-6 transgene that has impaired or lowered immune reactions against humans by allowing the urokinase-type plasminogen activator gene to be carried in an expressible manner therein; (iii) a method of liver injury induction by impairing the fumarylacetoacetate hydrolase (Fah) gene of the immunodeficient mouse expressing hIL-6 transgene that has impaired or lowered immune reactions against humans; and (iv) a method of liver injury induction by administering any of the compounds (a) to (e) below: (a) carbon tetrachloride; (b) acetaminophen; (c) d-galactosamine; (d) thioacetamide; and (e) anti-Fas antibody; and (a) carbon tetrachloride; (b) acetaminophen; (c) d-galactosamine; (d) thioacetamide; and (e) anti-Fas antibody; and