In a system supplying power from an AC power supply to a three-phase motor via a converter and an inverter, a leakage current reducing apparatus is connected to a connection line between the AC power supply and the converter. A common mode transformer detects, as common mode voltage, common mode current flowing from the AC power supply to the connection line. The common mode voltage is inputted to a voltage amplifier via a filter apparatus. Output voltage obtained by voltage amplification passes through a capacitor and then is applied as an AC component to a neutral point of capacitors connected in a Y-connection fashion, so as to have the same phase as that of the common mode voltage. Thus, current having the same phase as that of the common mode current is supplied via the capacitors to the converter through the connection line, thereby reducing the common mode current.