Abstract: A corrosion resistance tester for a coated metal material including a surface treatment film on a metal substrate includes: a container placed on the surface treatment film, and having a bottom surface in contact with the surface treatment film, the container including a plurality of water-containing electrolyte material holders that open through the bottom surface; the water-containing electrolyte material contained in each of the water-containing electrolyte material holders of the container, and being in contact with an associated one of a plurality of separate measurement target portions of the surface treatment film; a plurality of electrodes being each in contact with the water-containing electrolyte material contained in an associated one of the water-containing electrolyte material holders; an external circuit connecting the electrodes together; and a conduction means configured to conduct electricity to the metal substrate through the electrodes and the external circuit.

Abstract: Disclosed herein is a method of testing a corrosion resistance of a coated metal material including a surface treatment film on a metal substrate. The method includes: treatment of interposing a water-containing electrolyte material containing water, a supporting electrolyte, and a water penetration enhancer, between a surface of the surface treatment film of the coated metal material and an electrode; holding of the water-containing electrolyte material on the surface of the surface treatment film for one minute to one day; and electrical conduction from the electrode through the water-containing electrolyte material to the coated metal material.

Abstract: A humidity sensor for evaluating the degree of corrosiveness of an environment under a coating has a sensor body including a first metal material and a second metal material which have different standard electrode potentials and which are alternately stacked with an insulating material interposed therebetween. The sensor body has an outcrop in which layers of the first and second metal materials are alternately exposed with a layer of the insulating material interposed therebetween, the outcrop serving as a sensor surface. Humidity is detected based on a corrosion current which flows when a short circuit is caused between the first and second metal materials by humidity on the sensor surface.

Abstract: Disclosed is a humidity sensor for evaluating the degree of corrosiveness of an environment under a coating. The humidity sensor includes a sensor body including a first conductive material and a second conductive material which are alternately stacked with an insulating material interposed therebetween. The sensor body has an outcrop in which layers of the first and second conductive materials are alternately exposed with a layer of the insulating material interposed therebetween, the outcrop serving as a sensor surface. A voltage is applied between the first and second conductive materials, so that humidity is detected based on a current which flows when a short circuit is caused between the first and second conductive materials by humidity on the sensor surface.