High-resolution Fourier transform infrared spectra of the (NO3)-N-15 v(3)+v(4) and v(3)+v(4) v(4) bands were observed in the 1472 and 1112 cm(-1) regions. Compared with the case of N-14 species, large effects of perturbations were recognized in many rotational levels of the (NO3)-N-15 v(3)+v(4) state, and it was found that the v(2)+2v(4) state is responsible for the perturbation. Although a direct Coriolis interaction (Delta v(2) = 1, Delta v(3)(or Delta v(4))=1) is not present between these two vibrational levels, anharmonic terms including Phi 344 and Phi 444 mix v(3)+v(4) and 3v(4),v(2)+2v(4), v(2)+2v(4), and v(2)+2v(4) mixes with v(2)+v(4) to produce Coriolis interaction between v(3)+v(4) and v(2)+2v(4). An analysis gave the energy difference of 7.274 cm(-1) between two levels, and interaction parameters were determined. Similar perturbation analysis was applied for the 14N species, and the previous P-P(N,K) assignment of the v(3)+v(4) A'-v(4) E' band was changed for giving one A(2)', state. Spectral lines to another A,' state were not assigned because of weak intensity, which is explained by intensity anomaly through vibronic interaction, reflecting the transition moment of the (B) over tilde E-2'-(X) over tildeA'2. electronic band.