Large enhanced P violation in a nuclear resonance reaction has been observed by using a polarized neutron beam. Enhanced CP violation is predicted to exist within the same nuclear reaction. We are now preparing to supply a polarized neutron beam for a CP violation search experiment. In the enhancement process of CP violation, we assume that the P violation of the compound nuclear state doesn’t depend on the final state. However this assumption has not been verified yet. We plan to verify the assumption by measuring the $^{139}\rm La$(n,$\gamma$) reaction with a polarized neutron beam at J-PARC MLF BL04. The supplied neutron beam will be polarized by using $^{3}$He spin filter, which will be installed into BL04. We present the states of development for $^{3}$He spin filter and study of the equipment in BL04.