The nested Petri nets (NP-nets) are a nets-within-nets formalism convenient for modelling systems that consist of distributed mobile agents with individual behaviour. The expressiveness of the NP-nets formalism is greater than that of classical place/transition nets; and, the formalism allows to model open multiagent systems with agents being introduced, eliminated, and cloned. Several verification methods based on structural analysis and model checking techniques were developed for the formalism. But one of the basic structural methods for Petri nets analysis-traps-was not studied for NP-nets yet. In this paper we introduce NP-nets traps, study how to find them, and illustrate the analysis technique with a system of mobile agents.