A brake booster with regenerative brake force generation comprising a force input element coupled to a brake pedal. A chamber arrangement having a vacuum chamber and a working chamber that are separated from one another by a movable wall. A control valve actuated in accordance with a displacement of the force input element. The working chamber is connectable selectively to the vacuum chamber and the atmosphere to generate and reduce a differential pressure at the movable wall. The control valve has a control valve housing that is connected for joint movement to the movable wall. In a first actuation phase of the brake booster from its rest position, the force input element is displaceable relative to the control valve housing by an idle travel, in which the control valve remains non-actuated to suppress a build-up of a differential pressure at the movable wall.