This paper investigates friction characteristics of the linear ball guides. Linear ball guides are generally used for guiding linear motions of feed drive systems. In this study, friction characteristics of the linear ball guides are measured by using a core-less linear motor. As a result of the mathematical analysis, it have been confirmed that the friction force of the guides can be measured as a thrust force command in the experimental system. Measurement tests were carried out for three sizes of guides, three types of greases, three types of pre-load, and with or without of retainer. Firstly, relationships between velocity and friction force are discussed. As the results, it is clarified that the relationship between velocity and friction force depends on the grease viscosity, and the diameter of rolling ball. Non-linear spring characteristics in microscopic region are also measured. As the results of the measurement, it can be said that the non-linear spring characteristics depend on the size of the ball, pre-load, and retainer. The differences of the non-linear spring characteristics have influence on the vibration dumping of step responses.