An embodiment of manufacturing method of a flat-panel display device having a display panel and a transparent protector sheet; comprises: setting a bi-directionally Y-shape branched line pattern within a rectangular to-be-bonded area, which is formed of two Y-shaped intersections of a center line and angle bisector lines of the corners, of the to-be-bonded area; and applying adhesive resin onto the protector sheet or onto the display panel by forming circular or ellipsoidal dot patterns of applied adhesive resin so that: the dot patterns are arranged on the center-line segment and on the branch lines or their vicinities; and the dot patterns are arranged in symmetry with respect to the center line and to its perpendicular bisector.