PURPOSE: A fermentative feed mixing device is provided to improve packing device which maintains the inner pressure of a storage tank, thereby efficiently maintaining low temperature and pressure. CONSTITUTION: A fermentative feed mixing device comprises a tank body(110), a rotary shaft(130), a large sized ribbon blade and a miniature ribbon blade. The tank body is connected to a raw materials input hopper and an exhaust hopper. The rotary shaft is inserted in the center of the tank body and is rotated by a drive motor(120). The large sized ribbon blade is installed in a ribbon-shaped along a plurality of distal end parts of a first support and a plurality of end part of a second support. The miniature ribbon blade is installed in a ribbon-shape along the middle portion of the first support and a plurality of middle portions of the second supports. The cross sections of the miniature ribbon blade and the large sized ribbon blade are in a shape of trapezoid in which the upper side becomes gradually smaller tow
