  We study the negative refractive index in cubic noncentrosymmetric
superconductors. We consider the Maxwell equations under the Meissner effect,
and magnetoelectric effect arising due to broken inversion symmetry. We derive
dispersion relations of electromagnetic waves, and show that the refractive
index becomes negative at frequencies just below the Higgs gap. We find that
the chiral mechanism of the negative refractive index, which is usually
discussed in chiral materials with negative permittivity can be applied to
superconductors with positive permittivity by replacing the plasma gap with the
Higgs gap. Estimation from the experimental values of the penetration depth of
LiPt$_3$B indicates that the negative refractive index may appear in UV
regions. LiPt$_3$B may exhibit the negative refractive index at wavelengths
shorter than any other material observed so far.
