From the basic study on the rolling friction the main causes for rolling friction of linear ball bearing can be assumed as follows. (1) The variation of rolling friction which is due primarily to waviness and roughness of the rolling surfaces, and to the angle of relief of the bearing raceway. (2) The inherent bearing friction by the sliding friction which is due to the spinning between the rolling elements and the retainer except the variation in the friction force. In this study, the friction forces of the linear ball bearings in a low speed range by the factor (2) except the variation by the factor (1) were obtained from the recorded waves of reciprocate measurement of forward and reverse rolling. Moreover to clarify quantitatively the characteristics of the individual friction forming the rolling friction of this bearing, some experiments on the rolling friction behavior using a ball were performed. From the results of the above experiments and analyses, the friction characteristics of linear ball bearing can be explained. The sliding friction due to the spinning accounts for 70 to 75% of the total friction, and the pure rolling friction accounts for about 10 to 15%.