To substantially prevent the formation of white streaks even when a strong pulling force acts.

The method for connecting together two transparent or translucent sheets 11 and 12 formed with images consists in providing the sheets 11 and 12 with belt-like connecting together parts TA of a prescribed width along their edges, previously forming the images in the respective connecting together parts TA 1 and 2 in such a manner that the respective images overlap on each other when the connecting together parts TA of the respective sheets 11 and 12 are superposed and that the density of the superposed images is made approximate to the images exclusive of the images in the connecting together parts, then superposing and bonding of the connecting together parts TA 1 and 2 of the sheets 11 and 12.