Abstract: Disclosed are a light irradiation apparatus that prevents or suppresses projection of light on adjoining other portions and can be miniaturized overall, and a photocurable material treatment apparatus that includes this light irradiation apparatus. The light irradiation apparatus includes: a light source having a plurality of light emitting elements arranged in the x direction; and an elongated cylindrical lens extending in the x direction along the light source unit. A light source reference plane that includes a center of a light emission surface of each light emitting element is located on a plane separated in the y direction from a lens reference plane that includes a center axis of the cylindrical lens.

Abstract: Disclosed are a light irradiation apparatus that prevents or suppresses projection of light on adjoining other portions and can be miniaturized overall, and a photocurable material treatment apparatus that includes this light irradiation apparatus. The light irradiation apparatus according to the present invention includes, with three mutually orthogonal directions as an x direction, a y direction and a z direction: a long light source unit in which a plurality of light emitting elements are disposed in a state of being arranged in the x direction along a plane extending in the x direction and the y direction; and a cylindrical lens that has an elongated shape extending in the x direction along the light source unit, a longitudinal peripheral surface of the cylindrical lens including a light reception surface for receiving light from the light source unit and a light-exiting surface for allowing the received light to exit therethrough.