An air flow measuring device includes a measured passage and a sensor portion. Measured air which is a measuring object flows through the measured passage. The sensor portion is disposed in a sensor arrangement portion of the measured passage and is configured to measure a flow rate of measured air flowing through the measured passage. The measured passage includes an upstream bent portion on an upstream side of the sensor arrangement portion in a flow direction of measured air. The upstream bent portion includes an upstream throttle that partly decreases a passage area of the measured passage.