Among the rare earth elements there are six with even atomic numbers starting from neodymium, which possess atomic weights with poor uncertainties of ±0.02%. The present study aims at making precise mass spectrometric measurement of the six isotopic abundance ratios of samarium, attempting to correct the measured ratio, R_(150/152) of samarium, by the known true ratio, R_(151/153) of europium, and normalizing the six ratios so as to yield new isotopic abundance values and the atomic weight of samarium, 150.3548±0.0009. Among the rare earth elements there are six with even atomic numbers starting from neodymium, which possess atomic weights with poor uncertainties of ± 0.02%. The present study aims at making precise mass spectrometric measurement of the six isotopic abundance ratios of samarium, attempting to correct the measured ratio, R_ (150/152) of samarium, by the known true ratio, R_ (151/153) of europium, and normalizing the six ratios so as yield yield new isotopic abundance values ​​and the atomic weight of samarium, 150.3548 ± 0.0009.