There is provided a magnetoresistive film in which an interlayer coupling field Hin is minimized and a large regeneration output is produced. The optical writing apparatus includes a housing, an optical deflector, an f-theta lens and a separator. The end face of the optical waveguide is not made perpendicular to the light axis, and is diagonally cut so as to form an optical path conversion mirror. Each of them is for placing one LED chip.