A light irradiation device includes a light emitting unit, a cooling unit, a supply unit, and a driving unit. The light emitting unit emits light while generating heat. The cooling unit includes a channel through which a coolant flows, a first surface on which the light emitting unit is mounted, and a second surface that faces a direction opposite to the first surface. The supply unit is disposed facing the second surface in one direction that the second surface faces and supplies the coolant to the cooling unit. The driving unit is disposed facing the second surface in the one direction and includes a driving board that drives the light emitting unit.