Abstract: This actuator for an aircraft engine nacelle mobile structure (9) comprises a motor (1) intended to be mounted on a fixed part of the said nacelle, an endless screw (21) able to be turned by this motor (1), a slideway (5) intended to be connected to the said mobile structure (9) and comprising a nut (29) in mesh with the said endless screw, and a first ball end (15) allowing an angular offset between the axis of the said endless screw (21) and the said slideway (5). This actuator is notable in that it comprises a sleeve (19) able to accommodate the said screw (21) and extending with clearance inside the said slideway (5), the said nut (29) being mounted on that end of the said sleeve (19) that is closest to the said motor (1), and the said first ball end being interposed between the other end of the said sleeve (19) and the said slideway (5).