We investigated the electronic response of the quasi-two-dimensional spin gap compound ${\mathrm{La}}_{4}{\mathrm{Ru}}_{2}{\mathrm{O}}_{10}$ using optical spectroscopy. We observed the drastic changes in the optical spectra as the temperature decreased, resulting in anisotropy in the electronic structure of the spin-singlet ground state. Using the orbital-dependent hopping analysis, we found that orbital ordering plays a crucial role in forming the spin gap state in the non-one-dimensional material.