PHYSICAL QUANTITY DETECTION DEVICE

A physical quantity detection device for reducing an influence of a sound wave generated in a turbocharger and suppressing a decrease in detection accuracy of a physical quantity including a flow rate of gas. The device detects a physical quantity of air from an intake passage of an engine equipped with a turbocharger. The physical device includes a sub-passage that takes in part of air flowing from an upstream to a downstream side of the intake passage along a first direction, and a flow rate detection unit that detects a flow rate of the air taken in the sub-passage. The sub-passage includes an inlet that opens toward the upstream side in the first direction, an outlet that opens toward the downstream side in the first direction, and an attenuation chamber that attenuates a sound wave propagating from the turbocharger to an inside of the outlet.