Pure rotational spectra of ionic complexes, Ar-HN2+ and Kr-HN2+, have been observed using a Fourier transform microwave spectrometer combined with a pulsed-discharge nozzle, where Kr-HN2+ has been detected for the first time. The rotational constants, the centrifugal distortion constants, and the nuclear quadrupole coupling constants of the two nitrogen nuclei have been determined by least squares fittings for various isotopomers. The complexes have been concluded to have a linear proton-bound form, with the Ar-H distance in Ar-HN2+ to be 1.864 A and the Kr-H distance in Kr-HN2+ to be 1.948 A, respectively. Intermolecular stretching frequencies are estimated to be 199.2 cm(-1) for Ar-HN2+ and 198.7 cm(-1) for Kr-HN2+, respectively. Comparison of the results of Rg-HN2+ (Rg=Ar, Kr) with those of Rg-HCO+ indicates that Rg-HN2+ complexes have substantially stronger Rg-H interactions than those of Rg-HCO+. Furthermore, the derived nuclear quadrupole coupling constants suggest that there exists a sizable amount of proton transfer effect toward the Rg side in Rg-HN2+.