As an important source of food ingredients, it is necessary for soybean detection in foods because it was reported as one of the “big 8” food allergens. In this report, a PCR-based method was developed enabling the detection of even small traces of potentially allergenic soybean traces in food products. Soybean-specific primer was designed based on Gly m Bd 28K, one of the major allergens in soybean. The assay was applied to a wide range of food matrices and the detection limit was 0.01% (100ppm) for spiked peanut and whole milk samples, while it was 0.001% (10ppm) for skim milk, wheat and mung bean samples. It seems enough for soybean allergen detection in food matrices according to the threshold of soybean.