AIRFLOW MEASURING DEVICE

A case is equipped to an intake passage where a mainstream of air flows toward an engine. The case has a bypass passage which draws a part of the mainstream. A sensor is equipped to the bypass passage. The case has an external wall as a side wall extending along the mainstream direction in which the mainstream flows. The bypass passage has an outlet port formed in the side wall as an opening which opens in a direction substantially perpendicular to the mainstream direction. The airflow measuring device further includes a throttle located on the upstream side in the mainstream direction than a center of the opening to throttle a stream of air which flows outside the case along the side wall. The throttle throttles the stream of air to flow toward a downstream side and to merge with air flowing out from the opening.