Inertial device (1) for the stimulation of the pelvic floor muscles, designed to be inserted into a users vagina, comprising at least one hollow body (2) that contains at least one freely moving interior ball (3) that is able to move due to the force of gravity and the inertia of the users movements and to impact against an inner surface (4) of the hollow body (2). The inner surface (4) of the hollow body (2) comprises facets (5, 6) that form a certain angle with adjacent facets (5, 6) in a way that the interior ball (3) that is resting on a facet (5, 6) has to accumulate a certain amount of energy in order to move and hit an adjacent facet (5, 6). The device is effective and easy to manufacture, and it is also preferably symmetrical so that it is equally efficient irrespective of its positioning and the users morphology.
