A trap for catching animals, in particular muridae, is provided with a tank and a passageway, which extends above the tank from an entry and has, at the end, a container for a bait the floor of the passageway is defined by a gangway, which opens to let an animal fall into the tank and is provided with two trapdoors hinged to one another the first of said trapdoors is hinged about a horizontal axis, so as to tilt from a substantially horizontal position during the opening of the gangway, and has a counterweight to reclose the gangway the gangway has an attach device which connects the second trapdoor to a fixed retaining device, so as to support the first trapdoor in its substantially horizontal position even when the first trapdoor is subject to a weight the attach device is releasable when the weight rests on the second trapdoor.