A projection optical system (6) comprises a relay optical system (61), a PBS prism (71), and two projection lenses (81). The image light beam from a DMD (5) enters the PBS prism (71) via the relay optical system (61), is polarization-split there, and is directed to a screen by means of the two projection lenses (81). Displaying an image by means of the DMD (5) is controlled while the polarized states of the light beams produced by the polarization split by means of the PBS prism (71) are controlled. Thereby, a three-dimensionally viewable image and a high-resolution image created by pixel-offset can be projected. Since the relay optical system (61) is provided, the lens backs of the projection lenses (81) can be shortened, and the projection lenses (81) and further the projection optical system (6) can be made compact.