A relatively movable unit with rolling elements, or balls, adapted for use in a linear motion guide unit or a ball nut screw assembly. The relatively movable unit has lubricating rings disposed between any adjoining balls to thereby lubricate the balls. In the linear motion guide unit employing this relatively movable unit, the balls are confined in raceways at the interfaces between a track rail and a slider, while the lubricating ring is arranged between the adjoining balls. The lubricating ring is provided therein with spherical pockets opened to each other through a window at the center of the ring. The lubricating ring may be produced by forming a mixture of lubricant of turbine oil with resinous material of ultrahigh molecular weight polyethylene powder in a mold under pressure, and heating the molded mixture under pressure.