The invention relates to an actuator which is characterized in that the kinematic connection between the motor and the working element of the robot comprises a mobile link which is pivot fixed to the base of the actuator, a runner which is mounted to the mobile link and which may slide radially along the length thereof and a lever arm which is kinematically connected to the motor and which is hinge-connected to the runner by means of a pin. In this way, the rotation axes of the mobile link, the lever arm and the pin are parallel and said mobile link is kinematically connected to the working element. The distance between the lines that run alongside the rotation axis of the mobile link and the rotation axis of the lever arm may be greater or smaller than the length of the lever arm.