A Cardan shaft with safety device for agricultural or industrial use, comprising a shaft which is connected, at each of its axial ends, to a corresponding universal joint, the safety device comprising a safety cover that comprises a tubular body that is arranged around the shaft and is provided, at its axial ends, with two bell-shaped elements that are adapted to extend beyond the corresponding axial end of the shaft, the safety cover being uncoupled from the rotation of the shaft about its own axis, each one of the bell-shaped elements being slideable, with respect to the shaft, along the axis of the shaft, from an active position, in which it is extended beyond the corresponding axial end of the shaft so as to cover at least partially the corresponding universal joint, to an assembly position.