Chemical extraction using a molecular recognition resin named "Empore Radium Rad Disk"was developed to improve sensitivity for the low concentration of radium (Ra). Compared with the previous method, the extraction process speed was improved by a factor of three and the recovery rate for 226Ra was also improved from 81 ± 4% to > 99.9%. The sensitivity on the 10-1 mBq level was achieved using a high-purity germanium detector. This improved method was applied to determine 226Ra in Gd2(SO4)3 8H2Owhich will be used in the Super-Kamiokande Gadolinium project. The improvement and measurement results are reported in this paper.