An optical fiber of a bundled fiber light source is an optical fiber whose core diameter is uniform but whose emission end cladding diameter is smaller than an incidence end cladding diameter thereof, and a light emission region thereof is made smaller. An angle of luminous flux from this higher luminance bundled fiber light source, which passes through a lens system and is incident on a DMD, is smaller, i.e., an illumination NA is made smaller. Thus, an angle of flux which is incident on a surface that is to be exposed is smaller. That is, a minute image formation beam can be obtained without increasing the image formation NA, focal depth is lengthen.