An apparatus for detecting abnormal masses such as breast cancer includes a measurement sensor configured to obtain a voltage at a first area of a first breast of a subject； a reference sensor configured to obtain a voltage at a second area of a second breast of the subject, a position of the first area corresponding to a position of the second area； and a detector, wherein the detector includes a differential amplifier configured to amplify a voltage input from the at least one of the measurement sensor and the reference sensor； an active low pass filter configured to pass a signal frequency of a low frequency band among signals transmitted from the differential amplifier； a driver amplifier configured to amplify a signal passed through the active low pass filter； and an analog-to-digital (AD) converter configured to convert the signal amplified by the driver amplifier into a digital signal.
