A line filter capable of eliminating the common mode noise and the normal mode noise altogether. It comprises both the common mode noise elimination means and the normal mode noise elimination means. A central magnetic core 32 is provided in the middle flange 34 of bobbin 23. A through-window 36 is provided at a place facing the counterpart feet 27 of closed magnetic circuit core 28 so as a part of the central magnetic core 32 is exposed, but the central magnetic core 32 and the closed magnetic circuit core 28 are not making contact with each other.