In a flow quantity measuring device, each of upstream side and downstream side sensing resistors, which are placed on an upstream side and a downstream side, respectively, of a heating resistor, includes resistor elements, each of which forms a folded path. A coherent connection between the phase qubit and the charge qubit is provided. To prevent catching or snagging of the tube on the spigot preventing insertion, after forward motion of the spigot, the jaws are opened, and the spigot is retreated a short distance, the jaws are closed and the spigot is advanced again.