  Dynamical nature of the Josephson vortex (JV) system in
Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (Bi2212) has been investigated in the
presence of the c-axis current with magnetic field alignments very close to the
$ab$-plane. As a function of magnetic fields, the c-axis JV flux flow
resistance oscillates periodically in accordance with the proposed JV
triangular structure. We observe that this oscillating period becomes doubled
above a certain field, indicating the structure transition from triangle to
square structure. This transition field becomes lower in junctions with smaller
width perpendicular to the external field. We interpret that this phenomena as
the effect of the edge deformation of the JV lattice due to surface current of
intrinsic Josephson junctions as pointed by Koshelev.
