PURPOSE: To facilitate assembling by inserting a bolt from above a primary frame opposing to the secondary where a permanent magnet and a guide rail are arranged in the longitudinal direction in order to retain a linear bearing block on the primary and then adjusting the gap between the primary and the secondary sides.

CONSTITUTION: Many permanent magnets (not shown) are arranged, with alternating polarity, in the advancing direction between the guide rails 7 on the opposite sides (only one side is shown) of a secondary base 3 thus forming a secondary track. A primary runner R, to be guided on the guide rail 7, is constituted of a bearing block 9 and a primary frame 11 provided with an armature winding (not shown) in the center of the rear surface thus forming a permanent magnet linear motor 1. Four assembling bolts 17 are screwed into the frame 11 and the ends thereof are brought into contact with the linear bearing block 9. The gap between the frame 11 and the linear bearing block 9 is adjusted by rotating the bolts 17, a gap adjusting shim is inserted and a bolt 13 is tightened to set a predetermined gap and then the bolt 17 is removed.