We performed angle-resolved photoelectron spectroscopy (ARPES) studies on mechanically detwinned BaFe2As2. We observe clear band dispersions, and the shapes and characters of the Fermi surfaces are identified. Shapes of two-hole pockets around the Gamma point are found to be consistent with the Fermi surface topology predicted in the orbital ordered states. Dirac-cone-like band dispersions near the Gamma point are clearly identified as theoretically predicted. At the X point, split bands remain intactdespite detwinning, barring a twinning origin of the bands. Observed band dispersions are compared with calculated band structures. With a magnetic moment of 0.2 mu(B) per iron atom, there is good agreement between the calculation and the experiment.