The present invention, to provide that detects the resistance change on the surface of the photovoltaic module and at the same time measures the degree of contamination deposited on the module surface and efficiently secure a proper wash cycle of the PV module to the surface of the photovoltaic module a glass substrate which is provided to enable the attachment; Formed coating layer and the reaction able to cause the resistance change in accordance with the contaminant being contact with the coating on the one surface of the glass substrate and the laminate structure made possible contaminant on a surface on one side; A; is connected to the reaction coating layer pass the signal of resistance change and a signal processor for outputting a discrimination signal as to whether or not after measuring the amount of change in the resistance value from the resistance change in accordance with the contaminants stacked processing operations the signal of the reaction coating contamination provides a pollution measuring devices of the photovoltaic module surface included.