To investigate the food preservative effects of mustard seed(Brassica juncea), mustard seed were added to Kimchi. Titratable acidity of Kimchi treated with mustard seed was higher than that of non-treated control at initial stage, but it was lower than control after 2 days of fermantation. The number of bacteria and lactic acid bacteria increased rapidly at the initial stage of fermentation and reached plateau by 2 days of fermentation. The number of bacteria and lactic acid bacteria of Kimchi treated with mustard seed was lower than that of control, and the more mustard seed added the less bacteria and lactic acid bacteria were observed.