We investigated the electronic response of the quasi-two-dimensional spin gap compound La4Ru2O10 using optical spectroscopy. We observed drastic changes in the optical spectra as the temperature decreased, resulting in anisotropy in the electronic st
ructure 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.