Probes 4a and 4b having irregularities formed in leading end portions thereof are brought into contact with an electrode P of a device D, which is a target object to be inspected, at a predetermined probe pressure so that a mechanical damage is applied to an insulating film O on the electrode P. As a result, an electrical resistance value between the electrode P and the probes 4a and 4b is reduced to a first predetermined value or less. Subsequently, a fritting is performed to apply an electrical damage to the insulating film O on the electrode P so that the electrical resistance value between the electrode P and the probes 4a and 4b is set to be a second predetermined value or less which is smaller than the first predetermined value.