Subjects for the invention are to provide a light-modulating element having an elevated energy efficiency while preventing a decrease in contrast at low cost without using a display technique employing a waveguide or lightguide plate, and to provide a display element capable of producing high-quality display images and an exposure element capable of exposure treatment. In the invention, the light-modulating element comprises: a total-reflection optical member 2 having such a property that at least part of planar incident light introduced into the light-modulating element is totally reflected at an interface (total reflection plane) 22 of a layer constituted by the light-modulating element and the incident light does not substantially go out through the side opposite to the incident-light introduction side; and light-coupling elements 6 which are disposed on the total reflection plane 22 side of the total-reflection optical member 2 and serve to selectively couple with the incident light and take out the same from the total reflection plane 22.