It has been reported in a previous paper that a metal image was formed by a new peel apart system. In this system, the tonal range of image can be controlled from high to low ganma depending on the concentration of the photosensitive material of the sensor or heating time. This peel apart imaging system was based on the changes in the adhesive forces both between the base film and the methal layer and between the metal layer and the photosensitive layer, when the sensor was exposed to light and heated. For example, a positive type metal image was formed when poly (vinyl chloride) (PVC) and 2, 6-di (4'-azidobenzal)-4-methylcyclohexanone were used. In this case, by heating after imagewise exposure, the adhesive force between the metal layer and the photosensitive layer in the exposed area increased, whereas in the unexposed area the force was not changed. But the adhesive force between the metal layer and the base film in the exposed area became smaller than the adhesive force in the unexposed area by heating. A possible explanation is proposed that the photosensitive material and its photodecomposed products in the photosensitive layer cause these force changes.