Abstract: Precise measurement of jet angles plays an important role in events with two or more jets in final state, where the angles between individual jets has to be known to fully determine kinematics. This research studies the jet angular resolution of the ATLAS detector in proton-proton collisions with the center of mass energy  \sqrt{s} = 8 TeV. The results for full (Geant4) and fast (Atlfast-II) ATLAS detector simulations are obtained for different parts of the ATLAS calorimeter system as well as for different energies of jets and number of primary vertexes of event. Emphasis is made on comparison of full and fast simulations among them.