An object is to efficiently measure the resistivity of a transparent conductive film with high accuracy in a non-destructive and non-contact manner. Provided is a resistivity testing device that includes a light emitting device that emits p-polarized emission light having a wavelength selected by a preliminarily performed test-condition selecting method toward a transparent conductive film, formed on a light-transmissive substrate conveyed along a manufacturing line, from a film-surface side at an incidence angle selected by the method; a light detecting device that detects reflected light reflected at the transparent conductive film; and an information processor that calculates an evaluation value related to the amount of light of the reflected light with respect to the wavelength on the basis of the intensity of the detected light and obtains a resistivity from the calculated evaluation value by using a correlation characteristic in which the evaluation value and the resistivity are associated with each other in advance.