This paper presents an active filter with a compensator for unbalanced three-phase voltages of supply voltage. Main circuit is composed of a shunt active filter which is connected in parallel with the load and unbalanced voltage compensator which is connected in series with the line through a three-phase transformer, these parts are coupled with a smoothing capacitor. This paper first discusses the relation between the current control loop of the shunt active filter and total harmonic distortion (THD) of source current. The difference of the compensation characteristics for harmonic current between two current controls which have different detecting points are investigated. Then, the active filter with double current control loops is proposed and its THD have small value in comparison with the conventional active filter with only one current control loop. Finally, the validity of this active filter with the compensator for unbalanced three-phase voltages of the supply voltage is demonstrated with simulated and experimental results of the steady state.