An apparatus for measuring a biological signal of a body, the apparatus including at least three interfaces which obtain signals from the body, a signal application unit which applies a signal having a frequency which is higher than one of a frequency of interest of the biological signal to one of a first interface from among the at least three interfaces, and one of a plurality of internal elements of the apparatus, a feedback signal generation unit which generates a feedback signal from component signals generated due to the applied signal, wherein the feedback signal generation unit generates the feedback signal using a signal obtained from at least one of a second interface and a third interface from among the at least three interfaces and an input control unit which receives the generated feedback signal and controls a signal input from at least one of the second interface and third interface to an amplifier.
