Modulational instability (MI) of dust acoustic waves (DAWs), which propagates in an opposite polarity dusty plasma system, containing inertial warm negatively and positively charged dust particles as well as non-extensive q-distributed electrons and ions, has been theoretically investigated. The nonlinear Schrödinger (NLS) equation is derived by employing the reductive perturbation method. The NLS equation leads to the MI of DAWs as well as to the formation of DAW rogue waves (DARWs), which are formed due to the effects of nonlinearity in the propagation of DAWs. Both stable and unstable regions are revealed from the analysis of the NLS equation. It is observed that the basic features of the DAWs (viz. stability of the wave profile, MI growth rate, amplitude, and width of DARWs) are significantly modified by the various plasma parameters such as non-extensive parameter, electron number density, and electron temperature. The existence of the non-extensive electron/ion distribution creates an influence on the MI of the waves. It is observed that non-extensive distributed ions have more effect on the MI of the DAWs than electrons.