PURPOSE: To obtain a blocking device which can open/close a notched part, provided at the lower part of the front frame of a cubicle, for passing the draw out wheel of electric machinery regardless of the finish accuracy of the floor face at the lower part of door.

CONSTITUTION: A blocking board 5 sliding on the inner face of a beam 3 constituting the lower part of front frame to open/close a notched part for passing the draw out wheels of electric machinery is disposed on the inside at the lower part of the front frame of a cubicle 1. A cam 6 engaging with the blocking board 5 is disposed on the inside at the lower part of a door 2 so that opening/ closing of the door 2 causes movement of the blocking board 5 which then causes opening/closing of the notched part for passing the draw out wheels of the electric machinery.