A safety brake device for moving machine elements to prevent injury to the extremities of the operator of a machine if the distance of said operator from the moving machine element is less than a defined safety area. The device is characterized by an arrangement for detecting the operator position, in order to permit operation of the machine only if the operator remains within the defined working area, an arrangement for detecting the position of the extremities of the operator within a predefined safety zone, which enables the required work activities to be performed, and a brake device, by means of which the moving machine element can be immediately stopped if the extremities of the operator go beyond the safety area.