The present invention relates to a coupling structure for an electric case for a harrow for a rice planting machine, including: a shaft bracket having one axially coupled end and the other end fixed to a reinforcing member of a rotor cover such that pivoting can be performed at driving shafts on both sides of the electric case placed in the middle of the rotor cover a shaft member inserted into and coupled with the driving shaft of the electric case to be positioned outside the shaft bracket a fixed bracket having one end fixed to an upper surface of the electric case and the other end hinge axis-coupled with a supporting rod the supporting rod having one end hinge axis-coupled with the fixed bracket and the other end hinge axis-coupled with a link bracket and the link bracket hinge axis-coupled with the bottom surface center of the supporting rod with its body fixed to a link, in which a rotor is axially coupled with the shaft member. According to the present invention, the electric case disposed in the middle of the rotor cover is mounted on the rotor cover by the shaft bracket coupled with the driving shaft of the electric case and the electric case is supported and fixed by the fixed bracket coupled with the upper surface of the electric case, the supporting rod hinge axis-coupled with one end of the fixed bracket, and the link bracket hinge axis-coupled with an end of the supporting rod, and thus pressure applied to an input shaft of the electric case as a result of upward and downward driving of the harrow can be minimized, pressure applied to the driving shaft of the electric case is divided by the shaft member and the shaft bracket, and abrasion at the input shaft of the electric case and the driving shaft part can be minimized. Accordingly, the present invention can be used for long. In addition, the electric case does not have to be replaced as a whole in the event of the abrasion and some parts of it such as the shaft member or the shaft bracket have only
