A projection apparatus , configured to be disposed inside a dashboard, the projection apparatus comprising: a display device including: a light source configured to emit light; an image forming section configured to receive the light emitted from the light source and emit the light to form an image; and an optical element configured to diverge the light emitted from the image forming section ; and a free-form surface mirror configured to receive the diverged light, and to reflect the diverged light of the image and form another image; and a housing configured to house the display device and the free-form surface mirror , and to emit the light reflected by the free-form surface mirror ; characterized in that the projection apparatus further comprises: a positioner attached to the housing , the positioner being configured to position and hold each of the display device and the free-form surface mirror , wherein the positioner comprises holders for positioning and holding the display device and a mirror holder for positioning and holding the free-form surface mirror , such that the free-form surface mirror is detachable from the positioner without a change in relative positions of the image-forming section , the light source , and the optical element . a display device including: a light source configured to emit light; an image forming section configured to receive the light emitted from the light source and emit the light to form an image; and an optical element configured to diverge the light emitted from the image forming section ; and a light source configured to emit light; an image forming section configured to receive the light emitted from the light source and emit the light to form an image; and an optical element configured to diverge the light emitted from the image forming section ; and a free-form surface mirror configured to receive the diverged light, and to reflect the diverged light of the image and form another image; and a housing configured to house the display device and the free-form surface mirror , and to emit the light reflected by the free-form surface mirror ; characterized in that the projection apparatus further comprises: a positioner attached to the housing , the positioner being configured to position and hold each of the display device and the free-form surface mirror , wherein the positioner comprises holders for positioning and holding the display device and a mirror holder for positioning and holding the free-form surface mirror , such that the free-form surface mirror is detachable from the positioner without a change in relative positions of the image-forming section , the light source , and the optical element . a positioner attached to the housing , the positioner being configured to position and hold each of the display device and the free-form surface mirror , wherein the positioner comprises holders for positioning and holding the display device and a mirror holder for positioning and holding the free-form surface mirror , such that the free-form surface mirror is detachable from the positioner without a change in relative positions of the image-forming section , the light source , and the optical element . <EOS>