An object of the invention is to provide a thermal air flowmeter which can reduce a detection error occurring during pulsating air flow due to a difference of response between rising and falling of detected flow or due to air flow dependence of response. A thermal air flowmeter 1 includes a heat-generating resistor 7 which heats liquid, a heating drive circuit 5 which causes current to flow in the heat-generating resistor 7 and thereby controls heating of the heat-generating resistor 7, and a temperature-sensitive resistor 9 which detects a temperature of the fluid heated by the heat-generating resistor 7. The thermal air flowmeter 1 detects a flow Q of the liquid based on the amount of heat of the liquid heated by the heat-generating resistor 7. Further included are: flow correction value calculating means 17 which calculates a flow correction value ca based on a variation dQ/dt of the detected flow Q and on a flow correction coefficient a set dependent on the detected flow Q; and flow correction means 18 which corrects the detected flow Q based on the flow correction value ca.