A device for treating cellulite and stretch marks, includes: a unit (205, 215, 250) for placing a portion of the user's skin under negative pressure; a unit (205, 220, 50) for releasing the negative pressure and for placing the portion of the skin under relative positive pressure, including a plurality of chambers provided with a piston configured to strike the user's skin; and an element for controlling the negative pressure unit and the pressure-release and positive-pressure unit in order to produce cycles during which the negative pressure element and the pressure-release and positive-pressure element operate in turn. In some embodiments: the release unit includes an actuator controlling the position of the piston or the negative-pressure unit includes at least one chamber, which is provided, on one side, with a connection to a chamber placed under relative negative pressure.