Branching ratios of ions produced from the dissociative photoionization of N2O have been measured by using a time-of-flight mass spectrometer and synchrotron radiation in the 15–36 eV region. The branching ratios in the Franck–Condon gap (15.0–16.4 eV) indicate that the autoionizing Rydberg states in this region predissociate to NO+ and O+ through various dissociative states. The results obtained by the analytical photoion spectroscopy above the gap show dissociation pathways of the N2O+ ions. These pathways are discussed by comparing with the reported electronic states of ions and super excited neutrals.