To develope natural food preservatives antimicrobial effect of the natural products against food-related bacteria and yeast The purpose of this study was evaluate antimicrobial effect of the citrus seeds. antimicrobial activities of methanol extracts from the citrus seeds investigate against Escherichia coli O26, Staphylococcus aureus 6358, Saccharomyces cerevisiae IBM 4274, Bacillus licheuiformis 9945a and Alcoligenes faecalis. Citrus seeds is containing to moisture 4∼6.5%, curd protein 11∼15%, curd lipid 32∼46%, curd carbohydrate 22∼45 % and ash 2∼4 %, that is containing to flavornoid 12∼48mg% and phenolic compound 22∼53mg%. Solidity content of the methanol extract from the citrus seeds was 0.8∼1.2%. Almost all of the methanol extracts from citrus seeds exhibited growth inhibiting activities for most of microorganisms tested. The methanol extracts from Citrus grandis, C. sunki, C. sulcata showed the growth inhibitory effects against Escherichia coli O26. The methanol extracts from C. obovoidea, C. sulcata, C. aurantium showed the growth inhibitory effects against Staphylococcus aureus 6358. The methanol extracts from C. obovoidea, C. sulcata, C. tangerina showed the growth inhibitory effects against Saccharomyces cerevisiae IBM 4274. The methanol extracts from C. obovoidea, C sunki, C. sulcata, C. tangerinan, C. natsudaidai, C. iyo, C. aurantium showed the growth inhibitory effects against Bacillus licheuiformis 9945a. The methanol extracts from C. obovoidea, C sunki, C. sulcata, C. aurantium showed the growth inhibitory effects against Alcoligenes faecalis. Among this especially, Showed growth inhibiting activity of the methanol extracts from Citrus sulcata that about microorganisms investigated. If apply searching suitable application method about such the citrus seeds antimicrobial activity, role as good antimicorbial material in storage or cooking of food, processing is expected.