Biogenic amines (BAs) are produced primarily by microorganisms found in fermented foods and are often implicated in food poisoning. BA-producing bacteria found in fermented soybean pastes were isolated and characterized using a decarboxylating medium and multiplex PCR analysis. Two BA-producing bacteria were isolated from traditional soybean pastes: one was a histamine-producing Clostridium strain, and the other was a tyramine-producing Pseudomonas strain. The Clostridium strain was determined to be a potent histamine producer among the cultures tested. Synthesis of tyramine by Pseudomonas sp. T1 was observed for the first time in this study.