Abstract: A tattooing gun is described for use in tattooing the ears or noses of animals. The gun includes a spring-loaded driving shaft which is movable between cocked and uncocked positions. A driving link mechanism connects the driving shaft to the tattooing needles and needle support so that movement of the driving shaft from its cocked to uncocked positions causes the tattooing needles to be driven forwardly through a muzzle plate into the animal's ear or nose. Tattooing paste or the like is then rubbed on the wound caused by the tattooing needles.