The invention relates to an actuator having a gear mechanism converting a rotary motion into a linear motion, in particular for operating a clutch of a vehicle. According to the invention, on at least one axially movable element (A, B), the gear mechanism has at least one first guide element (B1), which corresponds with a second guide element (8.1) of a sleeve (C) having a torque support such that the first (B1) and the second guide element (8.1) engage with each other, wherein the second guide element of the sleeve extends helically about the drive axis, at least in part, such that the pitch of the second guide element is superimposed on the pitch of the gear mechanism.