To provide a high-performance screw pump flowmeter and to provide a method in which the generation of air bubbles is made constant and in which gasoline can be metered more precisely by controlling the temperature of a fluid.

In a gasoline metering machine, a screw flowmeter 4 is integrated with a high-performance screw pump 1. A fluid is guided smoothly by a low-speed rotation, and the generation of air bubbles as the characteristic of a fluid is continued stably. In addition, the gasoline metering machine is installed under the ground in which a temperature change is small. Thereby, the high- performance screw pump 1 continues a stable vacuum state so as not to generate an irregularity in its rotation. Consequently, a fluid at a set temperature and a set vacuum are held and continued, and a precise metering operation inclusive of air bubbles is guaranteed.