We determined the surface structure of SrF2(111) using low-energy atom scattering spectroscopy for insulator-surface analyses. For the spectroscopy, we used pulsed 3-keV 4He0 and 3-keV 20Ne0 beams as incident particles and detected 180° backscattered particles using a microchannel plate. We compared the experimental results with simulation results obtained using three types of surface atomic structural models: F–Sr–F, Sr–F–F, and F–F–Sr. Our results demonstrate that the topmost layer of SrF2(111) has approximately 60% and 40% of F–Sr–F and Sr–F–F, respectively.