With polarization-dependent soft X-ray absorption, we determined the orbital character of occupied and the lowest unoccupied eg orbitals of prototype single-layered perovskite LaSrMnO4. Our measurements indicate that LaSrMnO4 exhibits strong orbital polarization in the eg states of Mn3+ sites, leading us to conclude that LaSrMnO4 has a “ferro-orbital” ordering of 3z2-r2. We found that linear dichroism in soft X-ray absorption is an effective experimental method to identify the nature of orbital ordering in transition-metal oxides such as manganites.