Abstract: Disclosed is a flowrate sensor having a flowrate detection means built into a surface mounted package. The flowrate sensor includes a fluid flow path (70) formed in a package (12) to guide a fluid from an inflow port (30) provided in the lower surface of the package (12) to an outflow port (32) provided in the lower surface of the package (12) through the flowrate detection means; and an external terminal (40) provided in the outer surface of the package (12) to guide an electric output of the flowrate detection means therethrough. The flowrate sensor can be used for any of a liquid and a gas. The flowrate sensor is suitable for miniaturization, can be surface-mounted on an electronic circuit board or the like, and has a high reliability.