A line head, includes: a substrate which is provided with a plurality of luminous element groups which respectively include a plurality of luminous elements in a first direction which emit light beams; a lens array which includes a plurality of imaging lenses which are provided corresponding to the plurality of luminous element groups; and a light shielding member which is disposed between the substrate and the lens array and includes a plurality of light guiding holes which correspond to the plurality of luminous element groups, wherein the lens array is away from the light shielding member, an inner diameter of each of the plurality of light guiding holes in the first direction is a first light guiding hole diameter, and a bore diameter of each of the plurality of imaging lenses in the first direction is a first lens diameter, and the first light guiding hole diameter is smaller than the first lens diameter.