The objective of this study was to evaluate the antimicrobial effects of various natural flavonoids against growth of psy-chotropic Bacillus cereus strains, which cause dairy food outbreaks. Flavonoids were first screened for their ability to inhibitgrowth of B. cereus strains using the paper-disc diffusion test. Second, the growth inhibitory effect of selected flavonoidswas evaluated in tryptic soy broth supplemented with 0.6% yeast extract, and the bactericidal effect of the flavonoids wasmeasured in 0.8% (w/v) NaCl solution. Based on the paper-disc diffusion test, kaempferol was effectively active against B.cereus P14 and B. cereus KCCM 40935. Kaempferol had an antimicrobial effect at concentrations greater than 100 µM, andthe numbers of B. cereus P14 and B. cereus KCCM 40935 decreased by 3.55 and 1.5 log cycles, respectively. The cell num-bers of B. cereus P14 and B. cereus KCCM 40935 treated with 50 µM kaempferol were reduced by 4.18 and 2.84 log cyclesduring a 24 h incubation to test the bactericidal effect of kaempferol ( p<0.05). The results indicate that kaempferol had thegreatest antimicrobial effect among the psychotropic B. cereus strains and the natural flavonoids tested.Key words: psychrotrophic Bacillus cereus, kaempferol, flavonoid, antimicrobial effect, dairy food