A breath alcohol-measuring device for breathing gas sampling has a mouthpiece (2), for receiving the exhaled breathing air (1) of a test subject, provided with a first flow diaphragm (3). A first pressure sensor (6) is connected to the mouthpiece via a first gas line upstream of the flow diaphragm (3). An alcohol sensor (4) is connected to the mouthpiece (2) via an inlet channel downstream of the flow diaphragm (3) and to a sampling system (5) for a breathing gas sample from the breathing air (1) via a second gas line. The second gas line between the alcohol sensor (4) and the sampling system (5) has a second flow restriction (diaphragm 7) and is connected to a second pressure sensor (9). An evaluating and control unit (8) receives the measured signals of the pressure sensors (6, 9) and of the alcohol sensor (4) and actuates the sampling system (5). The sampling system (5) includes a bellows (10) with a piezo drive (30) and is actuated by the evaluating and control unit (8) as a function of the volume measured by means of the second pressure sensor (9).