The article presents the results of the study of the resistance of Bradyrhizobium japonicum (Jordan, 1982) and Sinorhizobium fredii (Scholla, Elkan, 1984) strains, selection of the FSBSI ARSRI of Soybean, to ammonium molybdate in a nutrient medium. In the variant without introducing a molybdenum salt, from 47 strains of rhizobia of the B. japonicum species, 37 strains showed good growth, 3 strains-abundant and 7 strains-moderate growth of the bacterial mass stroke. When 1 g/l of ammonium molybdate was introduced into the nutrient medium, the growth intensity of the bacterial mass stroke of all tested B. japonicum decreased slightly; the number of moderately growing strains increased to 11, and one poorly growing strain appeared. When 10 g/l of ammonium molybdate was introduced into the nutrient medium, the strains of B. japonicum, showing abundant and good growth of bacterial mass, were not detected. 31 strains of rhizobia of this species have stopped their growth. In the variants with a nutrient medium MRS without a molybdenum salt and with 1 g/l molybdenum salt from 44 strains of rhizobia of the species S. fredii 93-95 % of pure cultures showed abundant and good bacterial mass stroke growth. When 10 g/l of ammonium molybdate was introduced into the nutrient medium, no rhizobia strains of the S. fredii species were found with abundant and good growth of the bacterial mass, 12 rhizobia strains of this species showed poor growth, and 4 strains stopped growing at this concentration of molybdenum salt in the nutrient environment. It was established that ammonium molybdate at a concentration of 1 g/l in a nutrient medium, practically does not affect the growth intensity of the bacterial mass stroke of strains B. japonicum and S. fredii.