Abstract: A shredding machine comprises a housing, a shredding mechanism, a motor for operation of the shredding mechanism, a slot through which documentary material is fed for shredding by the mechanism, and an operating member movable from an operative position in which it extends across the slot, to an inoperative position retracted from the slot, in consequence of the feeding of the material into the slot, and returning, in the absence of the material in the slot, to its operative position under the action of a spring. A motor controller includes a microswitch having a plunger which is spring-urged into a projecting position, in which it is open circuit. The spring urges the operating member into its operative position. Thus, when material enters the slot, moving the operating member to its inoperative position, the plunger is depressed to start or permit operation of the shredding mechanism.