A movement-guiding device that includes a moving rail having a rolling element rolling surface; a first block that engages with the rolling element rolling surface of the moving rail via a plurality of rolling elements; a fixed rail including a rolling element rolling surface; a second block that engages with the rolling element rolling surface of the fixed rail via a plurality of rolling elements; and a joint member. The joint member is formed in a plank shape and connects the moving rail and the fixed rail by having the first block mounted on one surface and having the second block mounted on the other surface. The joint member is formed having a height difference.

In a linear motion guide unit, a raceway groove formed in a casing of a slider includes a first raceway surface extending along the length direction of the slider and a second raceway surface facing the first raceway surface and extending along the length direction of the slider. The second raceway surface includes a first portion including a center portion in a length direction of the casing, and a second portion including end portions in the length direction of the casing and having a wall surface shape different from a wall surface shape of the first portion. In the first portion, the first raceway surface and the second raceway surface define a symmetric Gothic arch groove, and in the second portion, the second raceway surface has a surface recessed from a position symmetric to the first raceway surface.