The energy spectra of neutrons emitted by thick targets of carbon, iron, copper, and lead at angles of 0, 15, 30, 45, 75, and 135 deg to the incident beam of 30- and 52-MeV protons were obtained by unfolding the pulse height distributions measured with an NE-213 scintillator. The angular distribution of neutrons above 3 or 4 MeV was obtained by integrating the measured spectra. The measured spectra were compared with a Monte Carlo calculation based on the Fermi free gas model of intranuclear cascades and evaporation. This comparison revealed that the calculated spectra are harder and stronger in the forward direction, but softer and weaker in the backward direction than are the experimental spectra. There is good agreement between the two at ∼75 deg. This experimental result showed that the calculational model is not adequate in the energy region below ∼100 MeV, where nuclear structure has a great influence on neutron production. The total neutron yield was obtained by estimating the neutron yield below a few million electron volts by fitting the spectra measured above that energy to the Maxwellian distribution and showed good agreement with other experimental results.