To reduce a movement resistance of a relative movement part and lengthen a relative movement distance in a linear motion bearing in which a shaft 1 is penetrated through a tube 2 such that it is relatively moved linearly in the state that it maintains a constant attitude.

A guide surface becoming a bottom part of a groove 20 axially formed on an inner periphery surface of the tube 2 is made opposed to an outer periphery surface of the shaft 1 and rollers 31 having an axis in a widthwise direction of the recessed groove are interposed on the opposed surface in a preload state. A return passage of the roller is penetrated and formed on a body part of the tube 2 on the back surface side of the guide surface and bent passages 40 for guiding the roller from a space between the guide surface and the outer periphery surface part to the return passage are provided at both ends of the tube. Roller installing apertures 38, 38 for rotatably installing rollers 31, 31 on a roller retaining belt 39 circulating and traveling along a circulation passage connecting these bent passages 40, 40 at both ends are formed.