The dielectric ic constant of CuGaSe2 as a function of stoichiometric deviations has been obtained from photomodulated spectral al ellipsometry measurements. Optical gaps have been computed by fitting experimental and differentiated data of the imaginary part of the dielectric constant to function epsilon (2) Of the Lorentz model and to the second derivative of epsilon (2). In each sample, three transition energy values have been found in the 1.65-1.72, 1.83-1.95, and 2.97-3.14 eV ranges. The presence of point defects I educes the energy gap values. For nonstoichiometric samples, changes in the first energy gap values have been analyzed as a function of the displacement of the position of the anion in the unit cell. The shirts in the valence band structure have been analyzed and it is concluded that the difference between the first and second transition energies, (E-g2-E-g1), is also affected by stoichiometric deviations, so that the Gamma ((2))(5v) level in samples with point defects is closer to Gamma ((2))(4v) level than in stoichiometric ones. Changes in (E-g3-E-g2) and (E-g3-E-g1) are related to Se position.