Low-temperature hydrogen plasma has been investigated under the conditions of electron cyclotron resonance by emission spectroscopy. The molecular distribution functions over the low rotational and vibrational levels of the hydrogen molecule in the triplet state have been measured. The translational, rotational, and vibrational temperatures of the ground and excited triplet states of the hydrogen molecule are determined. The obtained translational and vibrational temperatures indicate that low-temperature hydrogen plasma under the conditions of electron cyclotron resonance is a more efficient source of vibrationally excited hydrogen molecules in comparison with the other gas discharges.