PURPOSE: To achieve reduction of labor and largely improve work efficiency.

CONSTITUTION: In a device for forming a plurality of slits on a panel core member 3 which constitutes a frame of a wood panel, there is provided a core member feed mechanism to feed the core member 3 set on the starting point side of a straight operation line 1 in a longitudinal direction toward the end of the line 1. And a stopper mechanism 18 is provided in the line 1 to intermittently stop the member 3 in such a manner that said mechanism is gradually moved toward the end of the line 1. And a cutter 12 is provided on the starting point side of the line 1 to form a slit on the core member 3 as soon as the member 3 is stopped.