PURPOSE: To stably measure a flow rate without flow rate noises by coating a part of surfaces of an electrode of an electromagnetic flowmeter in touch with a liquid which does not face a flow passage with an insulating film.

CONSTITUTION: A surface of an electrode in touch with a liquid which is not seen from a flow passage is coated with a rigid insulating film. For instance, a side face part at a front end 9 of the electrode is coated with an insulating film 11 of 10-several hundreds μm thickness which adheres well to stainless steel, platinum or the like as a metal of the electrode. In order to apply the insulating film, a plastic or rubber insulating material is dissolved in an organic solvent and dried. Baking by heating is also carried out in some cases in order to enhance a strength of the coating film. Moreover, if a ceramic film or the like film is composed on the surface of the electrode through a vapor phase chemical reaction of a gas material, a further rigid coating is obtained.