a line filter assembly adapted to be inserted in an electrical power supply circuit of various electronic appliances for avoiding an invasion and leakage of noise includes first and second core members each having a pair of opposite arms connected together through a common bridge . coils are formed on the arms of each of the core members in such a manner that directions of magnetic fluxes produced in the closed magnetic circuit as a result of flow of line currents counteract while the same coils are so arranged that the magnetic fluxes produced in the closed magnetic circuit as a result of the flow of the line currents are oriented in the same direction .