The dietary effects of soy fiber beni-koji(SBCA) containing chitosan-ascorbate on the body weight and serum lipids in obese rats induced by a high fat diet were investigated. The experimental plots(6 rats per each group) were divided into a normal group(NC), a high fat diet group(HF), a 1% SBCA diet group(SBCA1) and a 2% SBCA diet group(SBCA2), and fed for 6 weeks. Compared with the HF group, the mean body weight and the $R'{o}hrer$ index of the SBCA1 and SBCA2 groups decreased by $3.4{sim}7.4%$ and $8.1{sim}13.9%$, respectively. In particular, the body lipids in the SBCA2 group decreased by 42.3%. The serum triglyceride content decreased by approximately $25.54{sim}27.34%$ in the experimental diet groups. There was no significant difference in the serum total lipids between the HF and SBCA1 groups. On the other hand, the total lipids in SBCA2 group decreased by 19.12% compared with the HF group. In the SBCA2 group, the total serum cholesterol and LDL-cholesterol content decreased by 6.57% and 41.20% compared with the HF group, respectively, while the HDL-cholesterol increased by 10.0%. The risk factor index(RFI) in the SBCA2 group was decreased remarkably by 58.57%.