A baler includes: a connecting unit installed at a front side of a frame, to which an axle frame, to which wheels are mounted, is connected to be moved freely, to be connected to a farming implement a hay collecting unit installed at a rear side of the connecting unit to collect hay for producing a dummy and a forming unit installed at a rear side of the hay collecting unit and having dummy rollers circularly disposed therein to form the collected hay into a cylindrical dummy, wherein a discharge door hingedly connected to a rear side of the forming unit installed at a rear side of the frame is opened and closed by a pair of discharge cylinders installed at opposite side surfaces of the frame and the discharge door.
