This paper is devoted to the study of estimation of internal conflict of evidence in the framework of belief functions theory. The decomposition approach, which was proposed early by the author, will be considered with this purpose. The establishment of some properties of this conflict measure is a main result of this paper. In particular, estimates of the upper bound of the internal conflict in the case of categorical evidence and bifocal bodies of evidence are obtained for decomposition with the help of Dempster’s rule and Dubois and Prade’s disjunctive rule.