PURPOSE: To make it easily usable in a simple structure and optionally embeddable in an objective spot by constituting a roller support shaft so as to cause its one end to be projected from the side of a support main body and to serve as a locating pin.

CONSTITUTION: At the time of application, a fixing shaft 25 is inserted into a fixing shaft insert hole 13 for a boss part 12 of a support main body 10, attaching it to a machine frame A or the like. At this time, a circular long hole (a) is preinstalled in the frame side in a radius ranging from the center of this fixing shaft 25 to the shaft center of a roller support shaft 15. At the time of installation, a projecting end 15' of this roller support shaft 15 is attached so as to be inserted into the long hole (a), and thereby a roller 20 is set so as to come into contact with an objective guide rail B. With such a position that a contact state between the roller 20 and the guide rail B comes to be smoothly operable, a nut 25' screwed in the fixing shaft 25 (mounting bolt) is clamped for fixation.