A light irradiation apparatus includes an optical power acquiring unit configured to acquire an optical power of light emitted by a light source and with which an object is irradiated an optical power adjusting unit configured to adjust the optical power of light emitted by the light source to a predetermined optical power in accordance with an acquisition result obtained by the optical power acquiring unit and an irradiation unit configured to irradiate the object with the light that is adjusted by the optical power adjusting unit.
