At the National Cancer Center, proton irradiation experiments have been conducted using the cyclotron accelerator to measure the neutron spectrum by the foil activation method. The experimental results demonstrate that high-energy neutrons are bombarded by injecting high-energy protons onto the tungsten target. The agreement between the results of the experiments and the MCNPX calculations with ENDF/B-VI is around 20% in the relative difference of the C/E (calculation/experiment) values in some of the Bi-209(n, xn)(210-x) Bi reactions. Here, the activation foil Bi-209 is useful in obtaining experimental neutron spectrum information on nuclear spallation reactions of the tungsten target by the high-energy protons ranging between 150 and 235 MeV. The current experimental data could contribute to evaluating the accuracy of the numerical simulation methodology of reaction rates and the uncertainties of cross sections of Bi-209, as experimental benchmarks.