Image information necessary to display a three-dimensional image of an object in a space is acquired with a simple structure, and a three-dimensional dynamic image in a true sense is displayed with a simple structure. Part of light from an object (10) falls on a polarizer (11). The polarizer (11) passes the component of the incident light polarized at a predetermined angle to the surface of the polarizer (11) and allows the component to emerge from the polarizer (11) as parallel light perpendicular to the surface of the polarizer (11). The parallel light passes through a condenser lens (12), a pinhole member (13), and a condenser lens (14) and falls on a CCD (15). The angle of incident light selected by the polarizer (11) can be changed with time. Therefore, the image information outputted from the CCD (15) is a set of items of two-dimensional image information including the direction of imaging changing with time and is necessary to display a three-dimensional image of an object in a space.