  Transition metal perovskite oxides display a variety of emergent phenomena
which are tunable by tailoring the oxygen octahedral rotation. SrRuO$_3$, a
ferromagnetic perovskite oxide, is well-known to have various atomic structures
and octahedral rotations when grown as thin films. However, how the electronic
structure changes with the film thickness has been hardly studied. Here, by
using angle-resolved photoemission spectroscopy and electron diffraction
techniques, we study the electronic structure of SrRuO$_3$ thin films as a
function of the film thickness. Different reconstructed electronic structures
and spectral weights are observed for films with various thicknesses. We
suggest that octahedral rotations on the surface can be qualitatively estimated
via comparison of intensities of different bands. Our observation and
methodology shed light on how structural variation and transition may be
understood in terms of photoemission spectroscopy data.
