A breath alcohol measuring device includes a flow chamber, for receiving exhaled breathing gas of a person, with a flow diaphragm. A differential pressure sensor has a first measuring connection via a first gas line (5) to the interior space of the flow chamber (2) upstream of the flow diaphragm (3), and a second measuring connection via second and third gas lines (12, 15) and a breath alcohol sensor (8) to the interior space of the flow chamber (2) downstream of the flow diaphragm (3). A throttling element (14) is present in the second gas line (12). The second gas line (12) is connected to a sampling system (9, 10), and an evaluating and control unit (6) is connected to the sensors (4, 8) and to the sampling system (9, 10) for controlling the sampling system.