The article investigates the issue in theoretical essence of the property rights pledge. The author connects the solution to a legal fiction «property right is the thing». It is argued that the property rights pledge is based on the absolute right of the pledger of the pledged property right as «ideal thing» (potential thing) and the limited right of the pledgee on the same property right («a thing»). The author suggests calling the theory of property rights pledge the Theory of Potential things based on the fact that property right advocates as a fiction of the thing within the structure of pledge.