A light irradiation apparatus includes: a rotary holding unit that rotates a substrate around a rotary axis while holding the substrate; a lighting unit positioned to face the rotary holding unit; a light shielding mask positioned between the rotary holding unit and the lighting unit, and widened along a direction orthogonal to the rotary axis; and a driving unit that linearly moves the lighting unit along the direction orthogonal to the rotary axis. The light shielding mask overlaps with the substrate when viewed in the direction of the rotary axis. The light shielding mask has an opening portion. An opening width of the opening portion at a side away from the rotary axis is larger than the opening with near the rotary axis. The lighting unit irradiates light through the opening portion toward the surface of the substrate while being moved above the opening portion by the driving unit.