We investigated a fracture of polymer nanocomposites filled with spherical nanoparticles (NPs). The dependences of the fracture on the interactions between the NPs and polymers were examined by coarse-grained molecular dynamics simulations in a deformed box with a Poisson ratio of 0.4. In order to observe the creation of nanovoids, the interaction among the polymers was set to be attractive. When the NP-polymer interaction is attractive, nanovoids appear in the bulk of polymers. On the other hand, for repulsive NP-polymer interaction, nanovoids are created at the surface between the polymers and NPs. At the same time, segregation of NPs is observed. We found that these behaviors depend on crosslink densities. (C) 2016 The Authors. Published by Elsevier Ltd.