A simply structured flowmeter in which an influence of a dilatational wave on a thermal flow rate sensor is suppressed, and measurement accuracy is enhanced.The flowmeter has not only the thermal flow rate sensor that is placed to face a flow channel and detects a flow rate of fluid flowing through the flow channel but also a micro path (for example, narrow pipe) that is provided to the flow channel and blocks a dilatational wave created in the flow channel from being transmitted to the thermal flow rate sensor.