To provide a method for preparing a rat model, exhibiting carcinogenesis of primary liver cancer and its metastasis to the lung as a liver cancer model that matches human clinical examination.

In this method for preparing rat model of lung metastasis induced by a primary liver cancer, a nitroso compound is infused a multiple number of times in the abdominal cavity of a rat, at a rate of 20-200 mg/kg-body weight for eachdose; while a period of 4 weeks or longer that is free of nitroso compound infusion after the final infusion is set to obtain the rat model of lung metastasis induced by a primary liver cancer. The nitroso compound is, preferably, diethylnitrosamine, and the evaluation of anticancer agent and antimetastatic agent can be carried out by using the model rat.