This study investigated the anti-obesity effect of a pear (Fructus Pyri Pyrifoliae) extract fermented by lactic-acid bacteria on obesity induced by a high-fat diet in rats. Body-weight measurement, blood analysis, and light microscope observation of adipose tissue in liver and epididymis were conducted after 8 weeks. Gene expression of leptin, adiponectin, and tumor necrosis $factor-{\alpha}$ ($TNF-{\alpha}$) in liver cells were also investigated. Compared to CON, PFA and PFB showed 8% weight reduction along with weight reduction of adipose tissue in liver and epididymis. Observing the microstructure of liver cells showed that lipid droplets were smaller in PFA and PFB than in CON. We confirmed that Fructus Pyri Pyrifoliae extract fermented by lactic-acid bacteria can affect gene expression of leptin, adiponectin, and $TNF-{\alpha}$ in liver cells, showing an obesity treatment effect. From the results above, it was observed that weight gain from increased gene expression in adipose cells as well as from the increased proportion of adipose cells caused by a high-fat diet can be statistically significantly reduced by taking Fructus Pyri Pyrifoliae extract fermented by lactic-acid bacteria. Therefore, Fructus Pyri Pyrifoliae extract fermented by lactic-acid bacteria can be effective for preventing and treating obesity by reducing weight and adipose cells.