The influence of annealing atmosphere on the crystallization behavior of amorphous structure in a-Si1-xGex thin films was studied with Raman spectroscopy. We annealed a-Si1-xGex (x=0, 0.14, 0.27) thin films at 800 degrees C under various atmosphere and observed change in Raman spectra. We confirmed that nitrogen-annealing atmosphere promotes crystallization of the a-Si film, however, the crystallization was not promoted in the annealing under Ar atmosphere and in vacuum. In the case of a-Si thin films containing Ge atoms, the crystallization in the a-Si1-xGex (x < 0.25) film was not promoted, although a-Si1-xGex (x=0.25) film was crystalized when the annealing in a N-2 atmosphere. However, crystallization of the a-Si1-xGex (x=0, 0.14, 0.27) were not promoted by the annealing under Ar atmosphere or in vacuum. The distortion induced by the presence of Ge atoms in the random-network of Si1-xGex, at a content below 25%, stabilizes the amorphous structure and obstructs the crystallization even in the annealing under the N-2 atmosphere.