An object is to improve measurement accuracy of a thermal air flow meter. A flow-rate measuring device comprising: a sensor assembly having a flow-rate detecting element; a circuit board on which the sensor assembly is mounted; and a housing on which the circuit board is mounted, wherein the sensor assembly is mounted on the circuit board such that a detection portion side of the flow-rate detecting element is closer to the housing, and the sensor assembly includes a contact portion in contact with the housing on the detection portion side.