The invention relates to a device (4) for actuating a control surface (2) of an aircraft, comprising: - a frame intended to be mounted fixed in relation to a structure of an aircraft, - a bell crank part (7) mobile in rotation in relation to the frame around an axis of rotation (X, X') and adapted in order to be connected to a mechanical unit (1) for displacement of the control surface (2), - a slider (6) intended to be connected to a drive member (5), the slider (6) being mobile in translation in relation to the frame according to a direction of translation, parallel to the axis of rotation (X, X') of the bell crank part (7), - first connecting means (61) between the slider (6) and the bell crank part (7) in order to convert a displacement in translation of the slider (6) generated by the drive member (5) into a displacement in rotation of the bell crank part (7), in order to actuate the mechanical unit (1) for displacement of the control surface (2),an input part (53, 16) able to be driven in rotation by the motor, - a control rod mounted fixed in relation to the frame and extending parallel to the axis of rotation (X) of the input part and at a distance from the latter, in order to block in rotation the slider in relation to the frame and authorize a translation of the slider in relation to the frame, the control rod extends through the slider (6). Application specific to the actuating of control surfaces incorporated into a thin airfoil.