A distance between a liquid crystal display panel set on a lower support mechanism and a front window set on an upper support mechanism is accurately determined by a stopper. An ultraviolet irradiation mask is provided on the front window. A part of the ultraviolet curable resin corresponding to a transmission pattern of the ultraviolet irradiation mask is temporarily cured through ultraviolet irradiation. The temporarily adhered structure of the liquid crystal display panel and the front window is taken from an attachment device to be left standing for a predetermined time period on a tray until an area and a thickness of the ultraviolet curable resin reach respective predetermined values. The ultraviolet light is then irradiated to an entire surface of the ultraviolet curable resin to finalize the adhesion. The time for which the attachment device is occupied is short, thus improving an operation rate of the device.