The protective effect of AI-1367 (Alnus japonica extract) on liver injury was investigated. Primary rat hepatocyte intoxication was induced by tert-butyl hydroperoxide (tBH), carbon tetrachloride ($CCl_4$), or D-glactosamine (D-GalN). Liver injury was induced by $CCl_4$, D-GalN or MCD (methionine choline deficient)-diet in mouse. The cellular leakage of lactate dehyrogenase and cell viability followed by the treatment of hepatotoxicants were significantly improved by AI-1367 treatment at a concentration range of 5~50 ${mu}g/ml$ for tBH, 5~50 ${mu}g/ml$ for D-GalN, and 5~100 ${mu}g/ml$ for $CCl_4$, respectively. Treatment with AI-1367 (20, 10, 5 mg/kg, p.o.) on liver injury induced by subcutaneous injection of $CCl_4$ or D-GalN reduced significantly the levels of aspartate transaminase and alanine transaminase in serum. Histological observations revealed that fatty acid changes, hepatocyte necrosis and inflammatory cell infiltration in $CCl_4$ (D-GalN)-induced liver injury was improved by administration of AI-1367. AI-1367 treatment (10, 5, 2.5 mg/kg, p.o.) also significantly recovered the body weight change and serum levels of aspartate transaminase, alanine transaminase and triglyceride in liver injury induced by MCD diet. From these results, AI-1367 shows protective effects against tBH, $CCl_4$, D-GalN, or MCD diet-induced hepatotoxicity in vitro or in vivo.