Abstract: A safety device for apparatus for driving fasteners, notably pneumatic nailing hammers and stapling guns, comprising feeler means substantially circumscribing the passage through which the fasteners are to be ejected. The feeler means are connected to the member controlling the release of the apparatus in such a manner that this release cannot take place unless the feeler means are pressed against a surface to be assembled. The feeler means consist of a plurality of independent feeler points which must be recessed simultaneously, otherwise the apparatus cannot be released. Only one of these feeler points is connected to the trigger of the apparatus and its retraction is normally prevented by positive locking means that cannot be released unless the other feeler points are depressed simultaneously against the force of resilient means urging them to their projecting position.