  We report ARPES results of the Fermi surface of Ca_{1.5}Sr_{0.5}RuO$_{4},
which is at the boundary of magnetic/orbital instability in the phase diagram
of the Ca-substituted Sr ruthenates. Three t_{2g} energy bands and the
corresponding Fermi surface sheets are observed, which are also present in the
Ca-free Sr_{2}RuO$_{4}. We find that while the Fermi surface topology of the
alpha, beta (d_{yz, zx}) sheets remains almost the same in these two materials,
the gamma (d_{xy}) sheet exhibits a hole-like Fermi surface in
Ca_{1.5}Sr_{0.5}RuO_{4} in contrast to being electron-like in Sr_{2}RuO_{4}.
Our observation of all three volume conserving Fermi surface sheets clearly
demonstrates the absence of orbital-selective Mott transition, which was
proposed theoretically to explain the unusual transport and magnetic properties
in Ca_{1.5}Sr_{0.5}RuO_{4}.
