PURPOSE: To maintain parallelism in a guide and a constant guide space for a guideway, and to improve accuracy.

CONSTITUTION: A straight line guide apparatus 1 includes two adjusting members, which are placed at an interval and capable of adjusting guide members 5a to 5f constituted as a damping element or guide unit in the direction perpendicular to the direction parallel to at least one of the guide members or in the case of a plurality of the guide members 5a to 5f are movable along a guideway, to the guide axis 7 of these guide members in common. The adjusting axis of the adjusting members crosses the guide axis 7 or lines parallel to the axis 7 or crosses at an equal spacing, and interval measurement instruments to measure the interval against a standard plane extending along the guideway are provided one each to a pair of adjusting members for each guide member or a group of guide members. Further, a comparator and an adjusting instrument for adjusting the adjusting members in response to the deviation from the standard value confirmed by the comparator are provided.