Soybean (Glycine max(L.) Merr.) is an important source of high protein and oil. Use of soybean meal bythe food industry is increasing, but severely limiting dietary choices and the quality of life of food-allergic individuals. Gly m Bd 30K (P34) is known as the main seed allergens in soybean-sensitive patients. The objective of this work was to determine the molecular basis of the low mutation of soybean P34 and to design polyclonal antibody for the selection of the causative mutations for wild homozygous, heterozygous and mutant homozygous. Using soybean genome assembly, we knew that soybean P34 genes are existing 2 copies in LG A1 and 1 copy in LG A2 in soybean genome. Actually, we confirmed that 3 copies for P34 gene were existed on soybean genome with Southern blot analysis. Glyma08g12270 of those was expressed at significantly higher level compared with Glyma08g12280 and Glyma05g29130by RT-PCR and western analysis. However this gene was not expressed in the low-P34 germplasm accessions. We develop a co-dominant marker based on the sequence of Glyma08g12270 containing a four-base pair insertion at the P34 start codon. Also, we make a polyclonal antibody for investigation of P34 protein levels. Further study, we will perform the crossing between low P34 accession and elite variety, backcrossing and allergen test using low P34 line.