Speckle noise is reduced to increase image quality in an image display apparatus such as a projection display or the like.An illuminating optical device in an image display apparatus (1) applies a laser beam L to a GLV (spatial modulator) (6) and modulates the laser beam based on an image signal input to the GLV to display an image. A plurality of laser beams (1, 1, . . . ) each having an optical path difference greater than the coherence length of the laser beam are applied to the GLV.