A linear motion guide unit is provided in which a crowning portion
available extensively for standard specification is made easily. The
crowning portion is comparatively small in depth, and rich in high
accuracy and high durability. A raceway groove for a load race in a
carriage is made at an ingress/egress area thereof with the crowning
portion of a curved profile that varies gently to allow the rolling
element to move in and out of the load race with smoothness. The carriage
is provided at the forward and aft ends of the raceway groove with
rounded bevels, which are made in a curved contour merging into the
associated crowning portion without causing any discontinuity at a
junction of the rounded bevel with the crowning portion.