When sardine meat which has a slight fishy odor was heated at 100°C for 30 minutes, it produced a bad strong fishy smell. Addition of 2 and 5% rice-fermented seasoning (RFS; Yushin brewery) suppressed the production of bad smell during heating. Peroxide value and content of dimethylamine (DMA) and trimethylamine (TMA) in sardine meats increased gradually during the heating and these increases were greatly suppressed by the addition of RFS. On the contrary, mirin and sake significantly suppressed the increase of DMA and TMA but had no effect on peroxide value. Effects of fermented seasonings including mirin type and sake type on absorbing TMA were determined as well as RFS. Although all tested seasonings absorbed TMA to some extent with increasing concentration, especially RFS had the most remarkable effect for absorbing TMA. RFS contained high concentration of total and amino nitrogens responsible for amino acids, peptides or proteins. In addition, RFS contained organic acids such as succinic acid, lactic acid, malic acid and acetic acid which could strongly abosrb TMA. This seasoning has higher buffer action than other tested seasonings owing to the compositional properties. These properties of RFS resulted in high activity of absorbing TMA. Among test solution such as amino acid, lactic acid or butylated hydroxyanisol modeled on a component of RFS, only lactic acid which suppressed TMA formation in heated sardine meat found to reduce strong fishy odor as well as RFS by sensory test.