Antimony selenide (Sb2Se3) has been proposed as an alternative material for a wide range of applications; however, the electronic structure of the Sb2Se3 lattice is not clearly known yet. As a consequence, there are abundant contradictory interpretations of experimental results leading to incoherent determinations of its energy band gap and the type of optical transitions. Moreover, Sb2Se3 is recently being synthesized in different types of nanostructures; therefore, detailed knowledge of the bulk electronic structure is necessary to evaluate deviations due to confinement or surface effects. In this paper, we study the electronic band structure of antimony selenide using density functional theory (DFT) within the generalized gradient approximation (GGA) with GW corrections. Our calculations show that Sb2Se3 has an indirect energy band gap of 1.21 eV; however, a direct transition only 0.01 eV higher than the band gap (1.22 eV) is also possible. The calculated density of states agrees well with the experiments reporting photoemission spectra.