It is very important for a cable puller to clarify the friction mechanism between a wire rope and steel grippers. In earlier works, some fundamental data such as friction coefficient, deformation and real contact area were obtained. This paper presents main factors affecting the friction based on the experiment varying apparent contact area and lubricants, and also observation of the deformation process. It is shown that the friction of the wire rope is hardly affected by the apparent contact area but significantly affected by the section shape of grippers. It is considered that high compressive load being mainly supported by 6 strands, rather than the rope core of a wire rope structure, is closely related to the friction mechanism.