The fabrication technique of Cr2O3-SiO2 coating as a tritium permeation barrier had been developed by chemical densified coating method. However, Cr2C3-SiO2 coating had open pores in the coating. For filling open pores, the densification treatment by CrPO4 was considered. From result of the deuterium permeation test, Permeation Reduction Factor (PRF) of SS316 with Cr2O3-SiO2 including CrPO4 coating reached about 1,000.