The output signal to interference-plus-noise ratio (SINR) of the minimum variance (MV) beamformer with one electromagnetic (EM) vector sensor in the presence of non-identical electric and magnetic noise power, which was not studied in Nehorai's earlier work [1], is derived in this aper. The state of polarization of the desired signal and interference under consideration are both assumed to be completely polarized. It is shown that the output SINR converges to that of a tripole antenna and a fairly high level near to infinite as the ratio of magnetic noise power and electric noise power approaches infinity and zero, respectively. It also has different sensitivity to the mismatch of sensor noise power for different types of states of polarization of the desired signal and the interference, e.g., in the circular, elliptical, and linear manner, and different DOA separation between the desired signal and the interference.