C.G.T., the french General Confederation of Labor, announced the Charter of Amiens(1906) that it would accept industrial federations only and not craft federations, and worked for the restructuring of labor organizations with a basis on such industrial unionism. Until 1914, C.G.T. went through intensified internal struggles around the two principles of craft unionism and industrial unionism. The majority of local labor unions remained as craft unions in spite of the incessant persuasion of their federal council while industrial unionism successfully settled down in a level of federation. Especially in big cities where strikes and labor disputes occurred frequently, craft unions played a great influence. In Paris, for example, showroom of various crafts and center of labor movement, by the beginning of 1914, 36 craft unions survived in the field of construction industry; variety of crafts never died away. Until the same year, they demonstrated their strong solidarity in a series of strikes, including the Paris general strike of construction workers in 1911. This shows that the separation of labor organizations according to craft-based identities does not necessarily weaken their power of class struggle. In short, the most remarkable characteristic of C.G.T. of the time, especially of the Construction Federation, was such a dual structure, craft organization at the level of local union and industrial organization at the level of federation. Craft unionism fought well against industrial unionism whose cause was the elevation of a revolutionary spirit by means of the unification of labor movements in conforming to the change of the economic conditions. To the workers of the time, this shows, crafts were not just the manifestation of mere professional profit and closeness but the foundation of communities which sustained their identity even in the time of full economic transformation. Considering Revolutionary Syndicalism of C.G.T. of the time, therefore, in the aspect of its structural base, one can see that the mainspring of labor movement was craft unionism, not industrial unionism as it is generally said.(Seoul National University)