The electronic structure of nearly optimally-doped novel superconductor LaO$_{1-x}$F$_x$BiS$_2$ (${it x}$ = 0.46) was investigated using angle-resolved photoemission spectroscopy (ARPES). We clearly observed band dispersions from 2 to 6 eV binding energy and near the Fermi level (${it E}_{rm F}$), which are well reproduced by first principles calculations when the spin-orbit coupling is taken into account. The ARPES intensity map near ${it E}_{rm F}$ shows a square-like distribution around the $Gamma$(Z) point in addition to electronlike Fermi surface (FS) sheets around the X(R) point, indicating that FS of LaO$_{0.54}$F$_{0.46}$BiS$_2$ is in close proximity to the theoretically-predicted topological change.
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