Angular magnetoresistance study has been a subject for intensive investigation, both theoretically and experimentally. According to the plane in which the magnetic field rotates, various unconventional features have been observed. More than half a dozen theories have been developed to explain the experimental results, but major parts of the phenomena are yet to be understood. In addition to the three sister compounds, (TMTSF)2X (X = ClO 4, PF6, and ReO4), that we have studied extensively, another member of the Bechgaard salt (TMTSF)2FSO 3 becomes particularly interesting because its angular magnetoresistance can only be understood with a two-dimensional electron model. We report the azimuthal angle dependence of its oscillations and determination of the cross section of the Fermi surface.