A light irradiation apparatus includes a light modulation element which modulates a phase of an incident light beam to obtain a V-shaped light intensity distribution having a bottom portion of a minimum light intensity, and an image formation optical system which applies the modulated light beam from the light modulation element to an irradiation target surface in such a manner that the V-shaped light intensity distribution is provided on the irradiation target surface. The light modulation element has such a complex amplitude transmittance distribution that a secondary derivative of a phase value of a complex amplitude distribution becomes substantially zero at the bottom portion of the V-shaped light intensity distribution in an image space of the image formation optical system.