[en] A shielding benchmark experiment has been performed using a quasi-monoenergetic ⁷Li(p,n) neutron source with the peak energies of 244 and 387 MeV at the Research Center for Nuclear Physics (RCNP) of Osaka University, in order to assess the accuracy of nuclear data and calculation codes used in high-energy accelerator shielding design. Energy spectra behind bulk shields of 10 to 100 cm thick iron, 25 to 300 cm thick concrete and their composite are measured using a NE213 organic liquid scintillator with a diameter and thickness of 25.4 cm each with a time-of-flight and an unfolding method. The comparison between the experimental data measured by the NE213 scintillator and a Bonner sphere spectrometer shows good agreement in the overlap energy region. The neutron attenuation lengths are illustrated for iron and concrete as a function of the incident energy. The attenuation lengths show signs of a plateau above 250 MeV for both