Solubility and chemical state of N in an N-doped Mg(x)Zn(1-x)O film were studied by using Raman and x-ray photoelectron spectroscopy. Three anomalous Raman peaks are observed at 272, 580, and 642 cm(-1), respectively, and are demonstrated to be only related to substitution of N for O site (N(O)) but not to substitution of N(2) for O site (N(2))(O). The solubility of the N(O) is dominated by Mg concentration and chemical potentials of N and O in growth condition. The chemical state of the N can change from coexistence of (N(2))(O) and N(O) to single (N(2))(O) with increasing Mg concentration.