Disclosed herein is a method for manufacturing a patterned object and a light irradiation apparatus that make it possible to form a pattern that accurately follows a mask pattern with higher accuracy in a patterning process of irradiating a pattern forming substrate with vacuum ultra violet light. The light irradiation apparatus includes a mask stage arranged apart from the pattern forming substrate and configured to hold a mask on which a prescribed pattern is formed, and a vacuum ultra violet light source unit configured to irradiate the pattern forming substrate with vacuum ultra violet light through the mask. A space between the mask and the pattern forming substrate is set to be an atmosphere containing oxygen. The vacuum ultra violet light source unit irradiates light, as the vacuum ultra violet light, having a continuous spectrum in a range where a wavelength ranges from 180 nm to 200 nm.