CANDLES aims to measure the very rare neutrino-less double beta decays using 48Ca which has the highest value among all isotope candidates. Low background techniques are the key to observe such rare phenomena. The largest background was found to be the high energy gamma rays from neutron captures on abundant material near the detector. The shielding system consisted of lead and B-contained rubber sheet was constructed to reduce the background. Performance of the constructed shielding system were described in this paper.