To provide a three-dimensional ion scattering spectroscopy and a spectrometer wherein it is possible to carry out a detailed structural analysis in a shorter time than before and to suppress the radiation damage given to the sample.

From the pulse ion beam source 1, pulse ion beams 4 are irradiated to a sample 3 housed in a vacuum chamber 2, and the scattered particles scattered from the sample 3 is measured by the three-dimensional detector 5 arranged at a prescribed distance separated from the sample 3. The three- dimensional detecting device composed of the three-dimensional detector 5, an electric circuit 6 of the former stage, and a computer 7 detects the scattered particles incident in the three-dimensional detector 5 at a time resolution 1.0 ns or less, calculates the energy of the scattered particles from its flight time, and detects the two-dimensional incident position of the scattered particles at a position resolution 360 μm or less.