The effect of the annealing temperature on the resistivity for stoichiometric (W2N), W rich (x<0.5), and N rich (x>0.5) tungsten nitride films (WNx) is different. The resistivity of as-deposited W2N is about 230 mu Omega cm and it increases slightly and then decreases with increasing the annealing temperature up to 900 degrees C. However, for the W rich WNx whose initial resistivity before annealing is around 145 mu Omega cm, the resistivity monotonically decreases with the annealing temperature increasing from 600 to 900 degrees C, As to N rich WNx whose initial resistivity is as high as 3000-5000 mu Omega cm, though the resistivity must decrease after annealing at 600-750 degrees C, it irregularly varies at the higher temperature range of 750-900 degrees C. The different annealing temperature dependence of the resistivity can be explained by considering the nitrogen desorption, conversion of WNx to pure W, and cracking of WNx films.