measurement in the measured water micro-region, creating a scanning probe microscope image, only carried out by contacting a probe on the image to fine regions, for measurement of the small current of less than pA, cantilever a sensor circuit for detecting a strain is useful as a guard electrode. For the second wiring for the sensor circuit using a magnetic detection type cantilever for detecting a variation of the first wiring and the cantilever for supplying a current to the probe, the guard potential for using a second wiring as a guard wiring of the first wiring and generation means, and a second wiring, a second wiring switching means for switching in time division a second period of time to maintain a first period, and a guard potential to be used as a sensor. Further, after obtaining a two-dimensional distribution in the first period, by first moving the probe to a predetermined position based on the two-dimensional distribution in the second period, and measure the current or voltage of the first wiring.
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