Collisional quenching of N2O+ A(2) Sigma(+)[(1,0,0) and (1,0,0)1 by He, Ne, Ar, Kr, N-2, CO, CO2, and N2O has been investigated by a flowing afterglow technique combined with a time-resolved laser-induced fluorescence technique. The quenching rate constants by He and Ne are found to be 2 or 3 orders of magnitude smaller than the corresponding Langevin rate constant; the same situation as in the quenching of CO+(A,upsilon=1). The quenching gases Ar, N-2, CO, CO2, and N2O, whose ionization potentials are lower than the recombination energy of N2O+(A), are found to deactivate N2O+(A) very efficiently, with a rate constant as large as the Langevin value. This fact would indicate the importance of the coupling between the N2O+(A)-Q and N2O-(X)-Q(+) states, where Q is a quenching gas. The rate constant for the quenching by Kr is much smaller than the Langevin value which can be ascribed to the unfavorable Franck-Condon factors between the N2O+ A(upsilon(1)’=0, 1)-Kr states and the high vibrational states of N(2)OX(upsilon ")-Kr+.