PURPOSE: To obtain a structure of a seat that posseses enough functions to serve both as a bed and a seat, by permitting a seat cushion to be moved back and a foot rest to be moved forward cooperatively with the backward tilting of a seat back.

CONSTITUTION: The seat cushion 3 of the seat is pivotted to arms 7 of the seat back 5. The foot rest 34 can slide in guide rails 4 of front legs 1. Working links 38 are pivotted to the undersurface of the foot rest 34, and are connected with the arms 7 of the seat back 5. The locking of the seat back 5 is effected by a gas spring 9. By operating the gas spring 9, the locking of the seat back 5 is released, and when the seat back 5 is tilted back, the seat cushion 3 is moved back, and the foot rest 34 is moved forward by the action of connecting rod 36.