Provided is a linear motion guide device that is less noisy and excellent in operability. A concave groove of a return guide and a raceway groove of a slider are not smoothly continued at a connection portion therebetween, where a stepped portion is formed. At a groove bottom portion of the raceway groove of the slider and the neighboring portion thereof, the surface of the raceway groove of the slider is located to be closer to a curvature center of the raceway groove of the slider than the surface of the concave groove of the return guide is. At a groove shoulder portion of the raceway groove of the slider and the neighboring portion thereof, the surface of the concave groove of the return guide is located to be closer to the curvature center of the raceway groove of the slider than the surface of the raceway groove of the slider is.