An impedance analyzer includes: a control voltage generating unit for generating a control voltage that has a predetermined amplitude value; a measuring unit operable to provide an output current, which has an amplitude value corresponding to that of the control voltage, for flowing through first and second body portions of a biological target, and to generate a measurement voltage that has an amplitude value corresponding to a difference between voltages at the first and second body portions attributed to flow of the output current therethrough; and a calculating module operable to determine an electrical impedance between the first and second body portions according to a predetermined adjustment value and the amplitude value of the measurement voltage.