The temperature dependence of the energy gaps for sulfur-annealed copper indium disulfide has been studied by photoreflectance in the temperature range of 10-300 K. The sulfur-annealed sample has been found to have larger transition energies, smaller positive temperature coefficients of energy gaps, and larger spin-orbit splitting energy than the as-grown sample. This can be explained by the reduction of d-level contributions in the upper valence band probably caused by the variation of lattice distance due to native defects.