A method and apparatus for measuring body fat using bioelectrical impedance, that reduces measurement errors and improves repeatability by compensating for variation of a contact voltage caused by variation of an electrode contact area. The method includes: detecting a voltage across the voltage electrodes under a first conditional pressure and a second conditional pressure to obtain a first conditional voltage and a second conditional voltage; determining the conditional pressures, a difference between the conditional pressures, the conditional voltages, and a difference between the conditional voltages to store them in a memory; detecting a measurement voltage under an arbitrary pressure; performing interpolation by using the conditional pressures, the difference between the conditional pressures, the conditional voltages, the difference between the conditional voltages, and the arbitrary pressure to obtain a contact voltage; and compensating the measurement voltage for the contact voltage to calculate a body fat value corresponding to the compensated measurement voltage.