PURPOSE: To simplify mechanism and reduce the dimension by pivotally installing the sector gears for forward and rearward elevation of a cushion seat, onto the lower brackets fixed onto a chassis and supporting a motor driving mechanism for turning individually each sector gear.

CONSTITUTION: Lower brackets 11 ate fixed onto the upper rail 13 of a pair of seat tracks 12 at right and left, and sector gears 17 and 18 for forward and rearward elevation of a cushion seat 20 are fixed at the both edges of two swing shafts 15 and 16 bridged in turnable ways between the right and left lower brakets 11. The sector gear 17 and the front part of the frame 21 of the seat 20 are connected through a link 22. A crank 26 is pivotally installed onto the rear part of the lower bracket 11 by a pin 25, and the arm part 26a and the rear part of the seat frame 21 are pivotally installed by a pin 27, and the arm part 26b and the sector gear 18 are connected through a link 28. The sector gears 17 and 18 are turned by motors 40F and 40R respectively.