PURPOSE: To finely perform regulation of output characteristic of a thermal air flowmeter, heighten rectification effect and speed effect and improve measurement precision.

CONSTITUTION: A guide cylinder 4 for guiding air flow to a main path 2 which becomes an air passage in a flow meter body 1 is provided, a venturi tube 3 is set in the guide cylinder 4 and a detection part 7 provided with a heating resistor 21 and a temperature compensation resistor 22 in the venturi tube 3 is arranged. An air receiving part 8 for receiving air allowed to flow from the side of the venturi tube is provided-facing the outlet of the venturi tube 3A and arranged thereat, an air gap 11 communicating with the main path 2 between the air receiving part 8 and the guide cylinder 4 is provided and an air flow hole 10 communicating with the main path 2 is set on the side face of the air receiving part 8.