A method for manufacturing a reflector array optical device, the optical device allowing a real image of an object being observed that is disposed toward one side of a principal plane to be formed in a space toward the other side of the principal plane, the method comprising: a step of forming at least two dihedral corner reflector array optical elements (6, 7, 8, 9), each of the dihedral corner reflector array optical elements (6, 7, 8, 9) including a substrate and a plurality of dihedral corner reflectors which each have at least two orthogonal side faces (61a, 61b), the orthogonal side faces (61a, 61b) being perpendicular to a principal surface of the substrate and orthogonal to each other, wherein the plurality of dihedral corner reflectors are integrated with the substrate so that orientations of interior angles of the orthogonal side faces (61a, 61b) are aligned with each other; a step of covering, with a masking material, the plurality of dihedral corner reflectors on the principal surface of the substrate adjacent to the end face of the substrate of each of the two dihedral corner reflector array optical elements (6, 7, 8, 9) to be adhered to each other; a step of bonding together the two dihedral corner reflector array optical elements (6, 7, 8, 9) while an adhesive is being supplied into between the end faces of the substrates to be adhered to each other so as to extrude part of the adhesive in between the end faces of the substrates from the surface of the masking material; and a step of removing the masking material from the plurality of dihedral corner reflectors on the principal surfaces of the substrates in conjunction with part of the adhesive, wherein the step of bonding includes a step of allowing the end faces of the substrates to be adhered to each other of the two dihedral corner reflector array optical elements (6, 7, 8, 9) to be brought into contact with each other before supplying the adhesive into between the end faces of the substrates, and allowing an adhesive tape to be affixed to and thereby couple between the principal surfaces of the substrates in such a positional relation as to bridge between the end faces of the adhered substrates; and with a coupled portion as a fulcrum, the coupled portion being provided by the adhesive tape before the two dihedral corner reflector array optical elements (6, 7, 8, 9) are bonded together, the end faces of the adjacent substrates are opened, and after the adhesive is supplied into between the end faces, the end faces of the substrates are closed and thereby bonded together. a step of forming at least two dihedral corner reflector array optical elements (6, 7, 8, 9), each of the dihedral corner reflector array optical elements (6, 7, 8, 9) including a substrate and a plurality of dihedral corner reflectors which each have at least two orthogonal side faces (61a, 61b), the orthogonal side faces (61a, 61b) being perpendicular to a principal surface of the substrate and orthogonal to each other, wherein the plurality of dihedral corner reflectors are integrated with the substrate so that orientations of interior angles of the orthogonal side faces (61a, 61b) are aligned with each other; a step of covering, with a masking material, the plurality of dihedral corner reflectors on the principal surface of the substrate adjacent to the end face of the substrate of each of the two dihedral corner reflector array optical elements (6, 7, 8, 9) to be adhered to each other; a step of bonding together the two dihedral corner reflector array optical elements (6, 7, 8, 9) while an adhesive is being supplied into between the end faces of the substrates to be adhered to each other so as to extrude part of the adhesive in between the end faces of the substrates from the surface of the masking material; and a step of removing the masking material from the plurality of dihedral corner reflectors on the principal surfaces of the substrates in conjunction with part of the adhesive, wherein the step of bonding includes a step of allowing the end faces of the substrates to be adhered to each other of the two dihedral corner reflector array optical elements (6, 7, 8, 9) to be brought into contact with each other before supplying the adhesive into between the end faces of the substrates, and allowing an adhesive tape to be affixed to and thereby couple between the principal surfaces of the substrates in such a positional relation as to bridge between the end faces of the adhered substrates; and with a coupled portion as a fulcrum, the coupled portion being provided by the adhesive tape before the two dihedral corner reflector array optical elements (6, 7, 8, 9) are bonded together, the end faces of the adjacent substrates are opened, and after the adhesive is supplied into between the end faces, the end faces of the substrates are closed and thereby bonded together.