Disclosed are a fetus electrocardiogram signal measuring method and its device that are capable of measuring the electrocardiogram signals of a fetus even during fetus movements and even at a gestational age during which the measurement current is weak, without the need for reattaching the electrodes and providing any shield room, even if the mother is a hospitalized or ambulant pregnant woman. The fetus electrocardiogram signal measuring device includes (1) high input impedance electrodes, (2) region-variable ground electrodes, and (3) a differential amplifier circuit and an optimization computing section.
