An airflow measuring apparatus includes a sub-passage that takes in part of flow of fluid flowing through an intake pipe, a sensor element disposed in the sub-passage to measure the flow of fluid, a circuit part converting the flow of fluid detected by the sensor element into an electric signal, a connector part connected to the circuit part to output a signal externally, and a casing supporting the sensor element and the circuit part. The sensor element is disposed in the intake pipe, and includes a cavity disposed at a semiconductor substrate and a diaphragm including a thin film part that covers the cavity. The sensor element on a lead frame has surfaces that are mold-packaged with resin so that the diaphragm and part of the lead frame are exposed. One hole is disposed at the lead frame for communication between the cavity and exterior.