Characteristics of the nuclear force responsible for the proton-proton scattering below 300 MeV are studied on the basis of the one boson exchange contribution model (OBEC-model). The partial transition amplitudes given by the model are so decomposed into five parts that each closely corresponds to central force, tensor, etc., in the usual potential approach. The differences between OBEC-model and the one boson exchange potential model (OBEP-model) are discussed by making use of these decomposed amplitudes. An analysis of the LS force and quadratic LS force from the OBEC-model suggests a possibility that the hard core introduced in conventional potential is unneccessary for all states except the singlet S-state.