A valve actuator includes moving equipment arranged to cause a plug of said equipment to slide along a given axis between two end positions. The moving equipment includes a core constrained to move in translation with the plug along the given axis. The actuator also includes a coil lying between two rings of ferromagnetic material, all three of which are secured to a frame of the actuator so as to surround the core, which itself carries two magnets mounted in opposition on the core level with the coil, a ring of ferromagnetic material lying between the two magnets that also lie between two other rings of ferromagnetic material. A valve and a machine may be fitted with such an actuator.