The present invention discloses a projection apparatus comprising: a light source for emitting illumination light; a mirror device comprising a plurality of mirrors for generating an image by reflecting the illumination light toward a projecting direction by means of a deflecting operation; and a projection optical system which is placed in the optical axis of reflection light in the projecting direction of the illumination light incident to the mirror device and which projects the reflection light, wherein the optical axis of the illumination light incident to the mirror device and the optical axis of the reflection light in the projecting direction forms an angle that is larger than the expansion angle α of the flux of the illumination light that satisfies NA=n*sin α, where NA is the numerical aperture of the flux of the illumination light, and n is the reflectance.