A new technique for quantitatively determining surface atomic structure to a precision of ∼±0.1 Å was developed by specializing low-energy ion scattering spectroscopy (ISS). It is termed low-energy impact-collision ion scattering spectroscopy (ICISS). This technique was applied to determine the relative positions of a Ti atom in the top layer and neighboring C atoms in the second layer of a TiC(111) clean surface. The result shows that the surface interlayer distance is smaller than the corresponding bulk value by 0.38±0.08 Å.