An electrostatic coalescing device including at least one pair of sheet-shaped electrodes arranged at a distance from each other side-by-side. Each one of the electrodes includes a sheet-shaped conductive member of electrically conductive material. The mutual distance between the conductive members of the two electrodes of the pair varies along the electrodes as seen in a direction perpendicular to the intended flow direction of fluid passing through the flow passage between the electrodes. A power supply is configured to apply mutually different electric potentials to the conductive members of the electrodes of the pair so as to form an electric field between the electrodes. The conductive member of one electrode of the pair is planar, whereas the conductive member of the other electrode of the pair is corrugated.