The apparatus of the invention is used for cardiopulmonary massaging and/or resuscitation of a patient and includes a massaging device (15) which can be reversibly driven in an actuating direction (23) by a drive unit (18) and which has a pressure surface (20) that can be placed in a target contact zone (21) on the rib cage (12) of a patient (11). In order to easily and reliably prevent the pressure surface of the massaging device to deviate from a target pressure point (21), the plunger (19) can be secured to the rib cage (12) of the patient (11) in the target contact zone (21) and is mounted in such a way as to be freely movable in a plane running transversely to the actuating direction (23) at least during an unloaded state between two massaging strokes.