PURPOSE: To draw out a casing cardboard at the forefront of the supplied cardboards and positively open the cardboard.

CONSTITUTION: Casing cardboards D loaded in a hopper device are pushed to the front of a bottom plate 31 by a retainer plate 33. When the cardboard D at the forefront is taken out by a suction pad 43, an upper edge of the cardboard D, while slightly bending, pushes an opening brush 301 away. Therefore, the cardboard D is positively opened because of the continuous resistance of the opening brush when the upper edge passes the opening brush 301.