The invention concerns a valve comprising a body (11) and a piston (12) movable in the body (11) between two extreme positions. One of the extreme positions is a so-called rest position or closed position and another extreme position is a so-called active position or open position. The valve (10) comprises at least one permanent magnet (20) on the one hand and at least one element made of a magnetic material on the other hand. One of the elements among the permanent magnet (20) and the magnetic element is integral with the body (11) of the valve (10), the other element being integral with the piston (12). The valve (10) further comprises a return element arranged to bring the piston (12) into its rest position when a force external to the valve, lower than a threshold value, is exerted on this piston (12). In a preferred embodiment, this return element is a spring (22).