In a finite linear motion guide unit, a retainer for retaining rollers rolling between guide members is formed into a V-like shape to thereby increase a rated load. A first guide member is formed into a V-like concave form, and a second guide member is formed into a V-like convex form. Needle rollers are retained by the V-shaped retainer and roll on a raceway formed by facing surfaces of the guide members. The V-shaped retainer includes a pair of roller retainer plate portions for retaining the needle rollers, and a retainer connection portion. A retainer straying prevention mechanism is composed of a pinion disposed in a cross-opening, and racks disposed on the guide members and meshing with the pinion.