This work presents the electrical properties of ZnO films according to the post-thermal annealing in the different ambient. We applied the post-thermal annealing in N₂ and air ambient to control the oxygen content of ZnO films, which improved crystallinity and optical properties of ZnO films. The oxygen concentration was measured by Auger electron spectroscopy and the electrical characteristics were obtained by Hall measurement in the van der Pauw configuration and transmission line method. As result, it was shown that the electron concentration varies from 10^(16) /㎤ to 10^(21) /㎤, while the resistivity from 10^(-3) to tens Ω·cm with respect to Zn and O concentration ratio. Also, thermal annealing in NH₃ ambient was carried out to form p-type ZnO films. ZnO films showed better crystallinity and electron concentration of 10^(15)-10^(17) /cm³ with thermal annealing in NH₃ ambient. These films were converted to p-type ZnO by activation thermal annealing process at 800 ℃ under N₂ ambient. The electrical properties of the p-type ZnO showed a hole concentration of 1.06 × 10^(16) /㎤, a mobility of 15.8 ㎠/V·s, and a resistivity of 40.18 Ω·cm. The N-doped ZnO films showed a strong photoluminescence peak at 3.306 eV at 13 K, which is closely related to neutral acceptor bound excitons of the p-type ZnO. In the SIMS spectra, the incorporation of nitrogen was confirmed.