TREAD MECHANISM FOR DOOR OPENING/CLOSING DEVICE

PROBLEM TO BE SOLVED: To facilitate installation of an automatic sliding door device which opens and closes with the stepping force of a passing person by making a necessary installation space smaller.SOLUTION: A door opening/closing device includes a tread 2 which is provided with a plurality of bearings, a link 5 which has one end coupled to a bearing 6 of the tread 2, and the bearing 6 which is provided at a floor fixation part and to which the other end of the link 5 is coupled. The tread 2 when stepped in moves down keeping itself in a horizontal state while being in arcuate motion in the moving direction of the passing person. A door 1 is opened and closed using the displacement as a power source. A return mechanism for the tread 2 comprises an extension link formed by extending the other end side of the link 5 in opposite directions from the tread 2, and a weight 7 supported by an extended end part of the extension link through a shaft. The weight 7 moves up as the passing person steps on the tread 2 to lower the tread 2, and moves down with its own weight as the passing person steps off from the tread 2 to move up the tread 2.