This study was aimed to investigate the effect of dietary $eta$-glucan obtained from bacterial fermentation on the adiposity and serum lipids level in dietary high fat induced obese rats. Experimentally, four weeks old male Sprague Dawrley rats fed high fat diet for 6 weeks to induce obesity, and subsequently fed one of three diets for further 6 weeks: 1) high fat control diet (0% $eta$-glucan) 2) 1% $eta$-glucan diet 3) 5% $eta$-glucan diet. For comparison, normal control group fed AIN-76A diet. Food efficiency ratio of rats were tended to be decreased with $eta$-glucan diet, but was not significantly affected. Visceral and peritoneal fat masses were lower in $eta$-glucan groups compared to high fat control group and the effect of $eta$-glucan was dose-dependent. Intake of $eta$-glucan increased HDL cholesterol level and significantly reduced adipocyte size, and free fatty acid, when compared to those of high fat control group. These results suggest that anti-obesity effect of $eta$-glucan may attributed to anti-lipogenesis.