Provided is a breast cancer diagnosis method comprising the following steps: attaching a measurement sensor unit to one side portion of a breast of a person to be inspected, attaching a reference sensor unit to one side portion of a breast opposite and symmetrical to the location on which the measurement sensor unit is attached, attaching a plurality of peripheral sensor units to a portion surrounding the location on which the measurement sensor unit, and measuring bioelectrical potentials inputting the bioelectric potentials, measured by the measurement sensor unit and the reference sensor unit, into a differential amplifier, amplifying the difference between the two potentials, inputting a bioelectrical potential measured by one of the peripheral sensor units and the reference sensor unit into the differential amplifier, and amplifying the difference between two potentials making only a signal in a low frequency band among signals transferred from the differential amplifier pass through an active low-pass passing filter amplifying the low frequency band signal by making the low frequency band signal, having passed, pass through a driving amplifier converting the amplified low frequency band signal into a digital signal by making the amplified low frequency band signal pass through an AD converter and measuring an average value of the bioelectrical potentials as the converted digital signal is input in a calculation unit. When the breast cancer diagnosis method of the present invention is used, the measurement distance is reduced, and, consequently, impedance between measurement signals is reduced. Therefore, signals can be stabilized in a short time. The measuring method is non-invasive, and a test can be performed within a short time. The breast cancer diagnosis method is harmless to the human body, is very efficient in aspects of time and economic efficiency, can perform a precision test on a portion to be inspected by adjusting the number of sensors, and can mi
