[en] Detail data on the polarization dependence on cumulative proton momentum and the mass number of a nucleus-target are stated. Incident proton energy is 640 MeV. The particle separation was performed according to the time-of-flight and energy absorbed with a NaI large crystal. Analysis of the proton spin state was carried out by the method of their repeated scattering at 12 deg +- 1 deg angle with a carbon target having known analyzing properties. Inclusive proton polarization was measured at 5 angles (from 58 deg to 150 deg l.s.) with the carbon target and at angles of 90 and 130 deg for Be, Al and Pb nuclei. The proton polarization dependence on the atomic number A of the nucleus-target decreases monotonously with the A growth. Data on the inclusive proton polarization obtained in the precumulative energy range do not contradict predictions based on the model considerations for the area of limiting nucleus fragmentation. However, to draw a finite conclusion, it is necessary to continue measurements at higher energies at higher statistical accuracies