PURPOSE: To return a seat back and a pillow part of the seat subjected to reclining operation to a regular erect attitude with one operation.

CONSTITUTION: This device constitutes a seat back reclining hinge mechanism 6 which attaches pivotally the lower end of a seat back frame 7 to a base frame 4 so that a backward reclining angle can be adjusted through a seat back seat lock cylinder 14, and also, can release a reclining operation by a seat back reclining release button 15. Also, this device constitutes a pillow reclining hinge mechanism 11 which attaches pivotally the lower end of a pillow part 9 to the seat back frame 7 through a parallel link mechanism 18, attaches pivotally one end of the parallel link mechanism 18 so that the backward reclinging angle can be adjusted through a pillow seat lock cylinder 19, and also, can release the reclining operation by a pillow reclining release button 20. In a leg base 2 for supporting a seat main body 1 so as to be free rotatable, a reclining release foot pedal 22 for releasing simultaneously the seat back seat lock cylinder 14 and the pillow seat lock cylinder 19 is arranged.