An image displaying apparatus, comprising: a light source; a light mixing element arranged on an optical path of illumination light emitted from the light source; a light condenser for condensing illumination light emitted from the light source to form a condensed light image at a predetermined position; a reflective image displaying element having plural micro-mirrors arranged two-dimensionally and configured to change an inclination angle of an individual micro-mirror between an on-state and an off-state so that emission of reflected light turns on or off; an illumination optical system including the light condenser and a first mirror for illumination and a second mirror for illumination, on the optical path of illumination light emitted from the light mixing element, the light condenser and a first mirror for illumination and a second mirror for illumination are arranged in such an order; and the illumination light transmits through the condenser lens and is reflected by the first mirror for illumination and the second mirror for illumination in this order, and the illumination light reflected from the second mirror for illumination irradiate the reflective image displaying element, and wherein an origin of an absolute coordinate system for each optical component constituting the optical system is provided at the center of a reflection surface of the reflective image displaying element, a longitudinal direction of the reflective image displaying element is the z-axis, a transverse direction of the reflective image displaying element is the x-axis and a normal direction of the reflective image displaying element is the y-axis, the first mirror for illumination is inclined with respect to both a direction of the x-axis and a direction of the z-axis, and wherein the second mirror for illumination is inclined with respect to both the direction of the x-axis and a direction of the y-axis; and a projection optical system for projecting, onto a surface to be projected, reflected light from the micro-mirrors being at an on-state among plural micro-mirrors constituting the reflective image displaying element, wherein the second mirror for illumination is arranged at a position nearest the reflective image displaying element on an optical path from the light mixing element to the reflective image displaying element and the second mirror for illumination is arranged in such a manner that an arcuate part of a ridge line of its reflective surface penetrates into the projection surface of the first lens of the projection optical system so that a part of light rays incident on the projection optical system is blocked by said arcuate part of the ridge line of the reflection surface of the second mirror for illumination when the plural micro-mirrors constituting the reflective image displaying element are all at an on-state. a light source; a light mixing element arranged on an optical path of illumination light emitted from the light source; a light condenser for condensing illumination light emitted from the light source to form a condensed light image at a predetermined position; a reflective image displaying element having plural micro-mirrors arranged two-dimensionally and configured to change an inclination angle of an individual micro-mirror between an on-state and an off-state so that emission of reflected light turns on or off; an illumination optical system including the light condenser and a first mirror for illumination and a second mirror for illumination, on the optical path of illumination light emitted from the light mixing element, the light condenser and a first mirror for illumination and a second mirror for illumination are arranged in such an order; and the illumination light transmits through the condenser lens and is reflected by the first mirror for illumination and the second mirror for illumination in this order, and the illumination light reflected from the second mirror for illumination irradiate the reflective image displaying element, and wherein an origin of an absolute coordinate system for each optical component constituting the optical system is provided at the center of a reflection surface of the reflective image displaying element, a longitudinal direction of the reflective image displaying element is the z-axis, a transverse direction of the reflective image displaying element is the x-axis and a normal direction of the reflective image displaying element is the y-axis, the first mirror for illumination is inclined with respect to both a direction of the x-axis and a direction of the z-axis, and wherein the second mirror for illumination is inclined with respect to both the direction of the x-axis and a direction of the y-axis; and a projection optical system for projecting, onto a surface to be projected, reflected light from the micro-mirrors being at an on-state among plural micro-mirrors constituting the reflective image displaying element, wherein the second mirror for illumination is arranged at a position nearest the reflective image displaying element on an optical path from the light mixing element to the reflective image displaying element and the second mirror for illumination is arranged in such a manner that an arcuate part of a ridge line of its reflective surface penetrates into the projection surface of the first lens of the projection optical system so that a part of light rays incident on the projection optical system is blocked by said arcuate part of the ridge line of the reflection surface of the second mirror for illumination when the plural micro-mirrors constituting the reflective image displaying element are all at an on-state.