PURPOSE: To stop the drive of a conveyer by pivotally disposing a foreign matter detecting member hard to break or deform on the back of a conveyer belt and detecting that foreign matter piercing through the belt collides with the member to be moved.

CONSTITUTION: A foreign matter detecting member 7 is pivotally disposed and supported by supports 8 in front of a carrier roller 6 brought into contact with the back of a belt 3 positioned just under a hopper 2. A control panel 10 is connected to a driving motor 4 and an abnormality detector 11. When acute foreign matter 14 pierces the belt 3, the foreign matter 14 is transported by the belt 3 to be collided with the foreign matter detecting member 7. Therefore, the member 7 is moved in the moving direction of the belt 3, so that a switch LS1 or LS2 is opened, which is detected by the abnormality detector 11. Whereupon, the driving motor 4 is stopped, thereby to stop the belt 3. Thus, the breakage of the belt 3 can be arrested to the minimum to prevent the belt from being fissured.