Spontaneous emission characteristics of hybrid InxGa1 − xN/Cd0.05Zn0.95O quantum well (QW) structures were theoretically investigated by using multi-band effective mass theory. The transition wavelength of the InGaN/CdZnO QW structure is shown to be changed from 415 to 580 nm when the In content x is varied from 0.1 to 0.3. The conventional InGaN/GaN QW structure shows that its peak intensity linearly decreases with increasing peak wavelength. On the other hand, the InGaN/CdZnO QW structure shows that the spontaneous emission coefficient reaches a maximum at around the peak wavelength of 0.484 µm, which corresponds to x = 0.2. This can be explained by the fact that, in a range of the short peak wavelengths, the InGaN/CdZnO QW structure has a very shallow potential well. In a range of the longer peak wavelengths above 0.47 µm, the InGaN/CdZnO QW structure is expected to have a larger spontaneous emission peak than the InGaN/GaN QW structure. This can be explained by the fact that the former has a reduced internal field compared to the latter.