A bioelectrode including a plate, a First electrode disposed on a first side of the plate, and a second electrode disposed on the first side of the plate and separate from the first electrode. The bioelectrode further includes a first guard portion disposed on a second side of the plate, a second guard portion disposed on the second side of the plate and separate from the first guard portion, and a preamplifier configured to output a voltage signal based on a biosignal measured between the first electrode and the second electrode.
