In this study, the denitration tests of the raffinate aqueous solution from he TBP solvent extraction part by formic acid were carried out to know the behavior of the minor actinides and the occurable troubles on the interface between the processes. As a result, the denitration reaction occured much more dratically comparing with the reaction in the cold tests. This was considered to be due to the presence of some amount of products of TBP destruction and some metal complex solvates with TBP. It was found that the optimum condition was the 1.5 molar ratio of [HCOOH]/[HNO3] and 2.5 hours denitration as the cold tests. At this condition, acidity of denitrated solution could be reduced to 0.44M, which provided a favorable condition for the followig steps of the partitioning process. Zirconium and molybdenum could be removed over 99% and 95%, respectively. Also, minor actinide elements as americium and neptunium were not precipitated.