Roasting temperature and time are important parameters in the process of roasted germinated brown rice flour (RGBRF), which cause the loss of bioactive ingredients and sensory value of the product. During roasting and storage, fat oxidation is also one of the problems that reduce the quality of RGBRF. In order to complete the RGBRF process, experiments using different temperature and time as 160oC, 200oC, 240oC for 10 to 30 mins were done to find the best roasting conditions. To limit the oxidation of fat during the processing and preserving RGBRF, ergothioneine (ERG) extract from enoki mushroom were supplemented at 3%, 5%, 7% and 10% (w/w) before roasted, the product was then ground and put into two types of packaging (PA and aluminum), vacuum seamed and stored at room temperature for 8 weeks were carried out. The results showed that germinated brown rice (GBR) which supplemented 3% of the extract before roasted at 200oC for 30 mins showed the best quality in term of sensory value, γ-aminobutyric acid (GABA) content and helped to limit fat oxidation as well as maintained stable quality after 8 weeks of storage in PA and aluminum packaging. In addition, the results from in vitro of starch resistance and in vivo of sugar absorption capacity in rats showed that RGBRF did not significantly change the GI index as well as the ability to absorb sugar compared to unroasted product. The results indicated that RGBRF should be used as a nutritious food with the ability to supplement bioactive compounds to the people at risk of lifestyle diseases.