  Structural properties of SmRu$_4$P$_{12}$ in the anomalous magnetic ordered
phase between $T^*\sim 14 $ K and $T_{\text{N}}=16.5$ K in magnetic fields has
been studied by x-ray diffraction. Atomic displacements of Ru and P, reflecting
the field-induced charge order of the $p$ electrons, have been deduced by
analyzing the intensities of the forbidden Bragg peaks, assuming a cubic space
group $Pm\bar{3}$. Also, by utilizing high-resolution x-ray diffraction
experiment, we observed a splitting of fundamental Bragg peaks, clarifying that
the unit cell in the magnetic ordered phase is rhombohedral elongated along the
$[1\, 1\, 1]$ axis. Responses of the rhombohedral domains to the magnetic
field, which reflects the direction of the magnetic moment, is studied in
detail.
