The Congo Red Agar method (CRAM), a method for detecting the presence of bacterial biofilm-forming capacity, does not provide sufficient knowledge on the criteria for each bacterial species. In this study, the biofilm detection capacity of the CRAM and the criteria for determining the presence of biofilm-forming capacity of bovine mastitis-causing bacteria were examined. 149 strains isolated from the milk of dairy cows with clinical mastitis were determined for biofilm-forming capacity using the CRAM. The Calgary Biofilm Device Method was also used as a comparative experiment. The study showed that the suitable medium and incubation time in the CRAM differed for each bacterial species, and the criteria for determining the presence of biofilm-forming capacity in each species could be determined.