PURPOSE: To miniaturize a runner and a hanger rail while preventing the generation of noises at the time of the operation of a seat by adjusting the angle of the slat without inserting a shaft to the runner.

CONSTITUTION: Slat driving shafts 39, 41 are borne to a runner case 40 supported to a hanger rail 1 rotatably in the vertical direction, the lower ends of the slat driving shafts 39, 41 are projected to the lower section of the runner case 40, and slats 3 are suspended and born to the lower ends of the slat driving shafts 39, 41. The base ends of turn arms 38 are set up at the upper ends of the slat driving shafts 39, 41, and said turn arms 38 are rotated, thus allowing the revolution of the slats 3.