This paper uses HexaM made by Toyoda Machine Works Co. as an analytical model of parallel mechanism type machine tools. Much collision may be generated for its complicated structure and working space, using this machine. For example, those collisions are generated between the moving components of the parallel mechanism, between the moving components and a workpiece and between the moving components and the tool storage for automatic changing. In this paper, an algorithm for detecting and avoiding those collisions is proposed. The method for avoiding the collisions is conducted by readjusting the location of the workpiece without amending the tool path. It is confirmed through experimental works that the proposed algorithm is useful for detecting the collisions and determining the location of the workpiece prior to the actual machining.