In the cross roller bearing, rollers are arranged crosswise with each roller perpendicular to the adjacent roller in a V groove. This design allows one bearing to receive loads in all direction. Since the cross roller bearing achieves high rigidity despite the minimum dimensions of the inner and outer rings, it is optimal for applications such as the joints of industrial robots, swiveling tables of machining centers and medical equipment. Although the cross roller bearing has high rigidity, friction torque is said to be high compared to other bearings. Studies of the friction torque of the cross roller bearing have hardly been published. In the cross roller bearing, it is said that preload affects friction torque, but preload measurement method of the cross roller bearing has also not been studied. In this study, the authors measure preload of the cross roller bearing with a newly developed method, and the relationship between tightening torque and preload was clarified. Furthermore, experiments on the influence of preload and grease components on friction torque were carried out. The results showed that, the influence of preload is small and the influence of kinematic viscosity of grease base oil is large.