Abstract: Device for generating seismic impulses for, for example, seismic prospecting, inside a hole or drilling well by impact of a weight or mass falling onto a target element coupled with a wall of the hole or drilling well. The target element is bound up with a variable volume anchorage element capable of being expanded so that it strikes against the wall of the hole or drilling well and is surmounted by a guiding column along which slides a hammer or weight forming the mass. A cable lifting system and magnetic devices enable the hammer or weight to be hoisted to a particular height above the target element.