It is an object of the present invention to provide a stereoscopic image displaying method and a stereoscopic image displaying apparatus using the same, which are capable of excellently observing a stereoscopic image. In order to achieve the object, a stereoscopic image forming apparatus of the present invention is configured such that display light from an image corresponding to a viewpoint of one parallax image on an image displaying device, on which parallax images corresponding to a plurality of different viewpoints can be displayed, is guided to an optical modulator, on which a light transmitting section and a light shielding section can be formed, by a second optical system disposed in the front of the image displaying device, and that the display light transmitted through the light transmitting section of the optical modulator is collected at a position that is a predetermined distance apart corresponding to the viewpoint on an observation surface by a first optical system, and the entire screen of a parallax image to be displayed on the image displaying device is thereby caused to be incident on each eye by controlling transmitted light from the optical modulator in synchronism with the switching of parallax images to be displayed on the image displaying device when an observer attains stereoscopic viewing of the image information on the image displaying device.