The complex refractive index of liquid and solid Sb2Te3 around its melting point has been measured by spectroscopic ellipsometry. The real and imaginary parts of the complex refractive index of liquid Sb2Te3 are totally different from those of solid Sb2Te3. The imaginary part of the complex refractive index for the liquid is significantly lower than that of the solid over the observed wavelength range. Our results are consistent with the idea that a molten area created in the center of a focused laser spot can function as a small aperture in the super-resolution readout effect in optical disks.