Non-alcoholic steatohepatitis (NASH) is characterized by accumulation of fat (steatosis), inflammation, and fibrosis in the liver without alcohol consumption. However, currently, there are no approved therapeutic agents for NASH in Japan, and it is considered there is no animal model that appropriately presents the complexity of NASH. Chimeric mice with a human hepatocyte (PXB-Mouse^®) are characterized by replaced mouse liver cells with human liver cells. They show the capacity to mimic the function of the human liver. Therefore, the animal could be an appropriate animal model for examining efficacy of potential therapeutic agents for NASH. The aim of the present study is to develop a NASH model using PXB-Mouse^® and evaluate the efficacy of pioglitazone. The study group of the NASH model was fed a choline-deficient L-amino acid-defined (CDAA, patented by our company) diet from Day 0 for 84 days. An efficacy study on pioglitazone was performed by oral administration from Day 0 for 84 days. Plasma AST, ALT, T-cholesterol, and liver HYP levels in the NASH model group were elevated compared with those of the control group. The pioglitazone-administered group showed decreased levels of plasma AST, ALT, T-Cholesterol, and liver HYP compared with those of the NASH group, suggesting that feeding PXB-Mouse^® with the CDAA diet induce the of NASH-like symptoms, and that pioglitazone treatment may have potential efficacy for NASH-treatment. It is concluded that the NASH model using PXB-Mouse^® could be considered a valid model for studying NASH.