To diversify the way of giving an initial motion to a door etc. in a door device for opening and closing the door etc. automatically after giving the initial motion.

An initial motion assisting mechanism 11 for giving the initial motion for opening/closing is provided near the door 2. As the initial motion assisting mechanism 11, a first power transmitting member 14a, which can be moved parallel to the direction of the movement of the door 2 via a wire 13a by stamping on a foot pedal 12a, is arranged. A first engaging member 16a fitted to the side of the door 2 is pushed by the first power transmitting member 14a, so that the initial motion can be given to the door 2 for its opening/closing operation. A pair of the initial motion assisting mechanisms 11 are arranged on the single door 2 to enable operation from both sides of the door 2.