A linear motion guide unit is disclosed in which a joint tube connects between a turnaround and a return passage of a sleeve made of sintered resinous material to ensure smooth turnabout of rolling elements and further in which lubricant can be supplied to the rolling elements for a prolonged period, thereby refining the durability. A slider is comprised of a sleeve for a return passage held with clearance fit in a through-hole of a carriage in a way lining major area of the through-hole with only forward and aft ends of the through-hole being left naked, a spacer with a lug having a radially inside curved half for a turnaround and an inside part for a joint tube to make up for any one end of the return passage joining with the radially inside curved half, and an end cap having a radially outside half for the turnaround and an outside part for the joint tube to make up for any one end of the return passage joining with the radially outside curved half.