PURPOSE: To provide the network controller in which a transient current produced in a DC block circuit of the network controller at the polarity inversion of a telephone line is reduced with simple circuit configuration.

CONSTITUTION: A network controller NA is connected between a telephone line L and a master control section 18 of a facsimile equipment vi a MODEM 15, a diode bridge 1 is provided to a pre-stage of a DC block circuit C provided to the network controller NA and a current in the same direction rectified by the diode bridge 1 flows to a bypass coil 2 of the DC block circuit C and even when polarity inversion takes place in the telephone line L, a large change in a transient current is suppressed to prevent malfunction of an exchange.