A display device includes a display panel displaying an image thereon and having a plate surface and including a panel alignment mark on the plate surface of the display panel, a polarizing plate disposed overlapping the plate surface and including a polarizing plate alignment mark, and a component disposed overlapping the plate surface and the polarizing plate and including a component alignment mark. The display panel, the polarizing plate, and the component have a non-quadrangular outline shape, a mounting position of the polarizing plate with respect to the display panel is determined according to position relation of the polarizing plate alignment mark and the panel alignment mark, and a mounting position of the component with respect to the display panel is determined according to position relation of the component alignment mark and the panel alignment mark.