In a droplet ejector equipped with an ejection port for ejecting minute droplets of a liquid, the ejection port 61 or the ejector and a conductor 10 such as a vehicle body are made electrically conductive to increase the electrostatic capacity of the ejection port 61 or the ejector and to suppress enlargement of the potential difference between the ejection port 61 and the liquid caused by flow electrification of the liquid. When the potential difference is large, a coulomb force acts between the electrified droplets and the electrostatically-charged ejection port, causing problems such as delayed or insufficient droplet discharge, but such problems are solved by increasing the electrostatic capacity of the ejection port 61 or the ejector.