A display apparatus to emit display light representative of an image which is displayed by the liquid crystal display element towards a transparent member and then display a virtual image of the image by the display light that is reflected by the transparent member, the display apparatus comprising: a liquid crystal display element; a light source to emit light which illuminates the liquid crystal display element from an opposite side to the display side of the image; an optical element (40, 51) which is disposed between the light source and the liquid crystal display element and on the optical axis of the light source; and a case body to house the optical element (40, 51), wherein the case body having: an opening which opens toward a first axial direction substantially orthogonal to the optical axis; a bottom section which is positioned on an opposite side to the opening in the first axial direction; groove sections (841, 843), each of which is positioned between the opening and the bottom section, extends along the first axial direction, and is hollowed in a second axial direction orthogonal to the optical axis and the first axial direction, wherein the optical element (40, 51) has a protrusion section (30a, 30b, 51a, 51b) which protrudes in the second axial direction, characterised in that the protrusion section (30a, 30b, 51a, 51b) is sandwiched by a groove section of the plurality of groove sections (841, 843), and is thereby housed in the case body while standing along the first axial direction, wherein a positioning section (40c, 51c) is provided at the bottom section's side of the optical element (40, 51), wherein a positioned section (O1, O2) at which the positioning section (40c, 51c) is to be positioned is provided at the bottom section, and wherein the positioning section (40c, 51c) and the positioned section (O1, O2) is positioned on the optical axis, when seen in the first axial direction. a liquid crystal display element; a light source to emit light which illuminates the liquid crystal display element from an opposite side to the display side of the image; an optical element (40, 51) which is disposed between the light source and the liquid crystal display element and on the optical axis of the light source; and a case body to house the optical element (40, 51), wherein the case body having: an opening which opens toward a first axial direction substantially orthogonal to the optical axis; a bottom section which is positioned on an opposite side to the opening in the first axial direction; groove sections (841, 843), each of which is positioned between the opening and the bottom section, extends along the first axial direction, and is hollowed in a second axial direction orthogonal to the optical axis and the first axial direction, an opening which opens toward a first axial direction substantially orthogonal to the optical axis; a bottom section which is positioned on an opposite side to the opening in the first axial direction; groove sections (841, 843), each of which is positioned between the opening and the bottom section, extends along the first axial direction, and is hollowed in a second axial direction orthogonal to the optical axis and the first axial direction, wherein the optical element (40, 51) has a protrusion section (30a, 30b, 51a, 51b) which protrudes in the second axial direction, characterised in that the protrusion section (30a, 30b, 51a, 51b) is sandwiched by a groove section of the plurality of groove sections (841, 843), and is thereby housed in the case body while standing along the first axial direction, wherein a positioning section (40c, 51c) is provided at the bottom section's side of the optical element (40, 51), wherein a positioned section (O1, O2) at which the positioning section (40c, 51c) is to be positioned is provided at the bottom section, and wherein the positioning section (40c, 51c) and the positioned section (O1, O2) is positioned on the optical axis, when seen in the first axial direction.