A guide track has a circular arc guide groove formed in a guide body. A movable body has two rows of rotating bodies that are separated in the width direction of the guide groove, and each row has a plurality of rotating bodies separated in the longitudinal direction of the guide groove. Each row of the rotating bodies is composed of an inner rotating body in rollable contact with a groove wall surface on the inner peripheral side of the guide groove and an outer rotating body in rollable contact with a groove wall surface on the outer peripheral side of the guide groove. The movable body is provided with thrust receivers making contact, in the groove width direction, with vertical wall sections of the guide body.
