An optical write line head includes multiple rows of light emitter devices lined up corresponding to respective positive lenses located in array form, wherein even with a fluctuation of its write plane in an optical axis direction, there is none of variations resulting from displacements of light emitting dots. A plurality of light emitter blocks, each including at least one row of light emitter devices lined up in a main scan direction, are located at a spacing in the main scan direction to define a light emitter array. On the exit side of the light emitter array, a lens array including one positive lens system in alignment with each light emitter block is located parallel with the light emitter array, and a write plane is located parallel on the imaging side of the lens array. A stop plate forming an aperture stop is located near a light-gathering position at which parallel light incident from the write plane side on each positive lens system comes together.