A phase shift analysis of p-p differential cross section, polarization and CKP measurements at 52 MeV is performed in terms of six parameters. Partial waves with L ≥3 are assumed to be correctly represented by the one-pion-exchange contribution with g2/4π= 14.4. The phase shift solution thus obtained is consistent with those at 68.3 and 98 MeV. The present solution together with those at 68.3 and 98 MeV seems to indicate that the effect of the spin-orbit force is not so strong below 100 MeV as at 310 MeV. This point is discussed in some detail.